Kingston RAM is known to be good for macs. Apple has a webpage where they tell you everything you need to know about what kind of RAM your computer has. If you can't figure out how to install it or need help purchasing it, check out Other World Computing (www.macsales.com). Note that their stuff is overpriced, but their instruction videos are great!
Are you sure your problem is the RAM? I just replaced the hard drive of a 2011 MBP with an SSD and it went much faster (I did a test - it booted three times as fast and opened Microsoft Outlook more than five times as fast. If you don't know that it's your RAM that needs upgrading, try running some tests and consider upgrading to an SSD first.