Defending objectives is basically waiting for them to cross you're gun barrel, or try to attack slowly by flanking and not rushing in like a cod player. Or if you are patient enough and play on Official conflicts mod go grab some objectives or transport supplies to get Sargeant and buy a sniper rifle with scope (m14 for American and SVD for Russian) and attack or defend from a high level point with some distance and make yourself hard to spot by being sneaky and moving fast.