In addition to deleting files, what can I do to speed up my MacBook?

Question

Hello!
My MacBook Pro (mid-2010 w/ 16gb of memory and 250gb hard drive) has been running really slow. I know I need to delete a ton of files as my internal disk is near full. My questions are:
My system report says the majority of disk space is being taken up by "Other". What can I delete to whittle that down?
How can I use this EtreCheck report to improve my MacBook's performance?
EntreCheck Report:
Problem description:
Mac is running slow.
EtreCheck version: 2.1.8 (121)
Report generated February 10, 2015 at 4:43:18 PM PST
Download EtreCheck from http://etresoft.com/etrecheck
Click the [Click for support] links for help with non-Apple products.
Click the [Click for details] links for more information about that line.
Hardware Information: ℹ️
    MacBook Pro (13-inch, Mid 2010) (Technical Specifications)
    MacBook Pro - model: MacBookPro7,1
    1 2.4 GHz Intel Core 2 Duo CPU: 2-core
    16 GB RAM Upgradeable
        BANK 0/DIMM0
            8 GB DDR3 1067 MHz ok
        BANK 1/DIMM0
            8 GB DDR3 1067 MHz ok
    Bluetooth: Old - Handoff/Airdrop2 not supported
    Wireless:  en1: 802.11 a/b/g/n
    Battery Health: Normal - Cycle count 832
Video Information: ℹ️
    NVIDIA GeForce 320M - VRAM: 256 MB
        Color LCD 1280 x 800
        2050W 1360 x 768 @ 60 Hz
System Software: ℹ️
    OS X 10.9.5 (13F34) - Time since boot: 9 days 19:34:17
Disk Information: ℹ️
    Hitachi HTS545025B9SA02 disk0 : (250.06 GB)
        EFI (disk0s1) <not mounted> : 210 MB
        Macintosh HD (disk0s2) / : 249.20 GB (24.95 GB free)
        Recovery HD (disk0s3) <not mounted>  [Recovery]: 650 MB
    MATSHITADVD-R   UJ-898
USB Information: ℹ️
    Western Digital My Passport 07B8 2 TB
        EFI (disk3s1) <not mounted> : 210 MB
        My Passport for Mac (disk3s2) /Volumes/My Passport for Mac : 2.00 TB (1.57 TB free)
    Apple Internal Memory Card Reader
    Apple Inc. Built-in iSight
    Apple Inc. BRCM2046 Hub
        Apple Inc. Bluetooth USB Host Controller
    Apple Computer, Inc. IR Receiver
    Apple Inc. Apple Internal Keyboard / Trackpad
Gatekeeper: ℹ️
    Mac App Store and identified developers
Kernel Extensions: ℹ️
        /Applications/AirParrot.app
    [not loaded]    com.squirrels.airparrot.framebuffer (3 - SDK 10.8) [Click for support]
    [not loaded]    com.squirrels.driver.AirParrotSpeakers (1.8 - SDK 10.8) [Click for support]
Problem System Launch Daemons: ℹ️
    [failed]    com.apple.wdhelper.plist
Launch Agents: ℹ️
    [not loaded]    com.adobe.AAM.Updater-1.0.plist [Click for support]
    [loaded]    com.divx.dms.agent.plist [Click for support]
    [loaded]    com.divx.update.agent.plist [Click for support]
    [loaded]    com.google.keystone.agent.plist [Click for support]
Launch Daemons: ℹ️
    [loaded]    com.adobe.fpsaud.plist [Click for support]
    [loaded]    com.adobe.SwitchBoard.plist [Click for support]
    [loaded]    com.google.keystone.daemon.plist [Click for support]
    [not loaded]    com.gopro.stereomodestatus.plist [Click for support]
    [loaded]    com.microsoft.office.licensing.helper.plist [Click for support]
User Launch Agents: ℹ️
    [loaded]    com.adobe.AAM.Updater-1.0.plist [Click for support]
    [failed]    com.apple.CSConfigDotMacCert-[...]@me.com-SharedServices.Agent.plist
    [loaded]    com.BlueStacks.AppPlayer.LogRotator.plist [Click for support]
    [loaded]    com.BlueStacks.AppPlayer.Service.plist [Click for support]
    [loaded]    com.BlueStacks.AppPlayer.UninstallAgent.plist [Click for support]
    [loaded]    com.BlueStacks.AppPlayer.UpdaterAgent.plist [Click for support]
    [loaded]    com.citrixonline.GoToMeeting.G2MUpdate.plist [Click for support]
    [running]    com.spotify.webhelper.plist [Click for support]
    [not loaded]    jp.co.canon.Inkjet_Extended_Survey_Agent.plist [Click for support]
User Login Items: ℹ️
    uHD-Agent    Application  (/Applications/BlueStacks.app/Contents/Runtime/uHD-Agent.app)
    uTorrent    UNKNOWN  (missing value)
    iTunesHelper    Application  (/Applications/iTunes.app/Contents/MacOS/iTunesHelper.app)
    Google Drive    Application  (/Applications/Google Drive.app)
    LivedriveCore    UNKNOWN  (missing value)
    Google Chrome    Application Hidden (/Applications/Google Chrome.app)
    WDDriveUtilityHelper    UNKNOWN  (missing value)
    EvernoteHelper    Application  (/Applications/Evernote.app/Contents/Library/LoginItems/EvernoteHelper.app)
Internet Plug-ins: ℹ️
    o1dbrowserplugin: Version: 5.40.2.0 - SDK 10.8 [Click for support]
    OVSHelper: Version: 1.1 [Click for support]
    Default Browser: Version: 537 - SDK 10.9
    Silverlight: Version: 5.1.20513.0 - SDK 10.6 [Click for support]
    FlashPlayer-10.6: Version: 16.0.0.305 - SDK 10.6 [Click for support]
    DivX Web Player: Version: 3.2.0.788 - SDK 10.6 [Click for support]
    Flash Player: Version: 16.0.0.305 - SDK 10.6 [Click for support]
    QuickTime Plugin: Version: 7.7.3
    googletalkbrowserplugin: Version: 5.40.2.0 - SDK 10.8 [Click for support]
    SharePointBrowserPlugin: Version: 14.3.6 - SDK 10.6 [Click for support]
    iPhotoPhotocast: Version: 7.0 - SDK 10.7
    JavaAppletPlugin: Version: 14.9.0 - SDK 10.7 Check version
User internet Plug-ins: ℹ️
    BlueStacks Install Detector: Version: 0.3.6 - SDK 10.7 [Click for support]
    CitrixOnlineWebDeploymentPlugin: Version: 1.0.105 [Click for support]
    Picasa: Version: 1.0 - SDK 10.4 [Click for support]
3rd Party Preference Panes: ℹ️
    Flash Player  [Click for support]
    GoPro  [Click for support]
Time Machine: ℹ️
    Skip System Files: NO
    Auto backup: YES
    Volumes being backed up:
        Macintosh HD: Disk size: 249.20 GB Disk used: 224.25 GB
    Destinations:
        My Passport for Mac [Local]
        Total size: 2.00 TB
        Total number of backups: 19
        Oldest backup: 2015-01-08 04:49:13 +0000
        Last backup: 2015-02-07 00:31:05 +0000
        Size of backup disk: Excellent
            Backup size 2.00 TB > (Disk size 249.20 GB X 3)
Top Processes by CPU: ℹ️
        13%    Finder
         9%    WindowServer
         3%    Google Chrome
         2%    coreaudiod
         2%    opendirectoryd
Top Processes by Memory: ℹ️
    464 MB    Google Chrome
    241 MB    Adobe Photoshop Lightroom 5
    210 MB    Google Chrome Helper
    137 MB    softwareupdated
    137 MB    Evernote
Virtual Memory Information: ℹ️
    336 MB    Free RAM
    5.96 GB    Active RAM
    5.62 GB    Inactive RAM
    2.50 GB    Wired RAM
    42.78 GB    Page-ins
    567 MB    Page-outs
Thank you!

Answer 1

"etrecheck" is of no use for solving this problem.
For information about the Other category in the Storage display, see this support article. If the Storage display seems to be inaccurate, try rebuilding the Spotlight index.
Empty the Trash if you haven't already done so. If you use iPhoto, empty its internal Trash first:
          iPhoto ▹ Empty Trash
Do the same in other applications, such as Aperture, that have an internal Trash feature. Then restart the computer. That will temporarily free up some space.
According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation—not the mythical 10%, 15%, or any other percentage. You also need enough space left over to allow for growth of the data. There is little or no performance advantage to having more available space than the minimum Apple recommends. Available storage space that you'll never use is wasted space.
When Time Machine backs up a portable Mac, some of the free space will be used to make local snapshots, which are backup copies of recently deleted files. The space occupied by local snapshots is reported as available by the Finder, and should be considered as such. In the Storage display of System Information, local snapshots are shown as  Backups. The snapshots are automatically deleted when they expire or when free space falls below a certain level. You ordinarily don't need to, and should not, delete local snapshots yourself. If you followed bad advice to disable local snapshots by running a shell command, you may have ended up with a lot of data in the Other category. Ask for instructions in that case.
See this support article for some simple ways to free up storage space.
You can more effectively use a tool such as OmniDiskSweeper (ODS) or GrandPerspective (GP) to explore the volume and find out what's taking up the space. You can also delete files with it, but don't do that unless you're sure that you know what you're deleting and that all data is safely backed up. That means you have multiple backups, not just one. Note that ODS only works with OS X 10.8 or later. If you're running an older OS version, use GP.
Deleting files inside a photo or iTunes library will corrupt the library. Changes to such a library must be made from within the application that created it. The same goes for Mail files.
Proceed further only if the problem isn't solved by the above steps.
ODS or GP can't see the whole filesystem when you run it just by double-clicking; it only sees files that you have permission to read. To see everything, you have to run it as root.
Back up all data now.
Install the app in the Applications folder as usual. Quit it if it's running.
Triple-click anywhere in the corresponding line of text below on this page to select it, then copy the selected text to the Clipboard by pressing the key combination command-C.
For ODS:
security execute-with-privileges /A*/OmniDiskSweeper.app/*/M*/* 2>&-
For GP:
security execute-with-privileges /A*/GrandPerspective.app/*/M*/* 2>&-
Launch the built-in Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
Paste into the Terminal window by pressing command-V. You'll be prompted for your login password.
The application window will open behind other open windows. When you scan a volume, the window will eventually show all files in all folders, sorted by size. It may take a few minutes for the app to finish scanning.
I don't recommend that you make a habit of doing this. Don't delete anything as root. If something needs to be deleted, make sure you know what it is and how it got there, and then delete it by other, safer, means. When in doubt, leave it alone or ask for guidance.
When you're done with the app, quit it and also quit Terminal.