Well,
Just make sure all background programmes are closed and delete all files/ uninstall programmes that you don´t need. There are many Boosters like "GameBooster" or other Tuning programmes.
In my opinion those programmes don´t help much.
I always:
-Uninstall softwares, that are not necessary
-Clean the registry with any programme (For example: Registry Cleaner)
-Defragment my PC ( I suggest "Disk Defrag"
-Close all background programmes (Also Antivirus if I don´t use a hack)
-Clean my PC ( Programmes, like "CCleaner"
Exactly what Philong said... Those things increase your FPS steadily... If you need Gamebooster, it is available for download in my signature.
~Closed...
If those don't help, then I recommend you get an upgrade or get more RAM...