Here's a few hint's you should try to remember whilst playing OFP: Elite....
Reload after EVERY firefight.
Try using stealth when engaging a large group of enemies, otherwise you'll just get ganged up on.
Unless your in a rush, take your time in missions, rather than running the whole way through. You'll loose accuracy when your trying to regain your breath, if you walk you'll have just about full accuracy.
Don't forget to use your fellow soldiers, Team Leader or just a private, who cares.
That's all the hint's for now, have fun, and play hard!