The key to good cooling isn't having more fans, it's having them placed correctly.
For example, you could put 20 fans in your case but if they are all poorly configured then it won't do you any good.
You want fresh air coming in and moving across the components, then quickly exiting the case. If you have warm air circulating inside the case then it's only going to make parts hotter.
With that said, make all your front and sidepanel fans intake, and rear and top fans exhaust. Remember that hot air rises, so if at all possible, keep the intake fans lower than the exhaust fans.
Also note that you need quality fans. Anything under 30 CFM is a waste of plastic. You want 50CFM+ and then you have some decent fans. If you have 120mm fan spots available, you can get 100+ CFM 120mm fans.
Also keep the dust out of your fans and components. Some people recommend fan filters to keep the dust out. Personally, I don't like fan filters because they hinder air flow....but if dust is a big problem in your area, then maybe you should try them.
Good wire management helps also. If you have tons of wires and cables in the way, then your airflow is going to get *stuck* on it, and not move freely within the case.
If specific parts are too hot (like your CPU, graphics card, etc) then maybe you should get some Arctic Silver 5, and a better heatsink.
Good luck.