I can think of one easy solution, don't play games with a ton of applications open. Keep only the necessary ones open and close the ones that you don't need open while gaming. 8Gb RAM should be plenty for some PC games.
I included the required and recommended specifications for what seem to be the most popular games among most age groups. You can find out which games you can run just by googling "random game pc requirements". You can check your memory usage by opening a task manager (Ctrl+Alt+Delete) and then opening the "Performance" tab. That way you can figure out which applications you can keep open while gaming. Hope this is helpful.