the biggest thing is, that you should only shoot at what you know for certain you can hit. the most important aspect of that is that most of the assault rifle weapons in the game are only effective at a point range of about 150-200 at the very most which is far, and unless you know what your doing, mechanics wise, you will only score a few hits , one or two maybe 3. On the flip side they are effective to about 230-260 by area and then they start to loose it, or the game deletes the round itself. I would love to access DICE's weapon archives in the programming section to see how accurate the weapons actually are, because in this game most engagements take place, at about 30-75 meters away from each other, and im many cases, even less than that like in titan mode.
I just picked up the sniper rifle to try to learn how to snap shoot people at short ranges and i am at about 56-57% with >600 kills which I plan to greatly increase. I think the sniper rifles in this game are not used correctly, your not supposed to park your ass on a tower and shoot at people, in the real world, a marksman is always on the move, bobbin and weavin' just like balls says lol