Selective cloning of the system (HDD to SSD)

Question

Hello there! First things first, my system is:
MacBook Pro9.2 (mid 2012) [13inch, non-Retina]
OSX Yosemite 10.10.1
Now the situation: I have stock 500gb HDD, which is almost filled. Im planning on buying a smaller SSD (256gb) [thinking of Crucial - just in case] to install it as my primary disk, having HDD aboard in Optibay.
The question is: what is the best (if there is exact) way to copy the system and essential user data/apps/settings (incl. Keychain and stuff) to a new smaller drive? (avoiding as much as possible additional backups, temporarily erasing things that exceed the space limit, moving data here and there to create a smaller partition and whatnot). In other words, what tool is more suitable to do such selective cloning, be it Time Machine (I have this option, the whole BU is bigger than 256gb), Migration Assistant, Disk Utility or 3rd party stuff like CCC/SuperDuper etc.?
Thanks!

Answer 1

Install OS X Using Internet Recovery
Boot to the Internet Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.
Partition and Format the hard drive:
Select Disk Utility from the main menu and click on the Continue button.
After DU loads select your newly installed SSD (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed. Quit DU and return to the main menu.
Reinstall OS X: Select Reinstall OS X and click on the Install button. Be sure to select the correct drive to use if you have more than one.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.
This should restore the version of OS X originally pre-installed on the computer.
See the following to finish:
How to use an SSD with your HDD
If you are going to use an SSD as a boot drive together with your existing HDD as the "data" drive, here's what you can do.
After installing the SSD you will need to partition and format the SSD using Disk Utility. Then, install OS X on the SSD. After OS X has been installed boot from the SSD. Use Startup Disk preferences to set the SSD as the startup volume.
Open Users & Groups preferences. Click on the lock icon and authenticate. CTRL- or RIGHT-click on your user account listing in the sidebar and select Advanced Options from the context menu. You will see a field labeled "Home dir:" At the right end you will see a Change button. Click on it. In the file dialog locate the Home folder now located on the HDD (HDD/Users/account_name/.) Select the folder, click on Open button. Restart the computer as directed. When the computer boots up it will now be using the Home folder located on the HDD.
Another more technical method involving the Terminal and aliases is discussed in depth here: Using OS X with an SSD plus HDD setup - Matt Gemmell. This is my preferred approach because I can select which of the Home's folders I want on the HDD and which I don't want. For example, I like to keep the Documents and Library folders on the SSD because I access their content frequently.
Be sure you retain the fully bootable system on your HDD in case you ever need it.