Don't know which component to upgrade first.

[Touchinghippo]

Recently I purchased new parts for my pc, but it isn't really giving me the fps I want for the games I play, I was wondering what you guys think I should upgrade first: My cpu, my videocard, or my ram for a budget of about $150

 

[Touchinghippo]

Forgot to mention my specs:
Cpu: AMD Athlon II X3 450
Videocard: EVGA Nvidia Geforce GT 620 2GB
RAM: Can't recall the brand, but it's a stick of 4gb with 1600Mhz