Yeah RAM is cheap and does help with the speed that your computer handles applications.
May I suggest the website where I bought my RAM? They're the most legit RAM sellers on the internet. www.crucial.com
They have tools that can scan your computer to show you what you already have/how many slots you have open.
They also have a tool that, when you put in all your computer details asked, will give you the exact RAM model(s) that are compatible with your computer.