I think sound knowlege is one of the best skills to learn. It goes hand in hand with map knowledge. For example, say you are on dm1, if at any time you hear a small health pick up, they MUST be down by the rail water pool as that is the only place in the map the small health packs are at. Same with the armor shards, if you hear that pickup, there are only two places the opponent could be, by the hyperblaster shards or by the mega shards. A person with good sound skills coupled with map knowledge is force to be reckoned with as it will almost seem as if they are walling you to find where you are. There has been a few times where people have called me a waller just cause I can distinguish what sounds come from where on a map. It works better when there are small amounts of people playing a map. When you get into larger amounts of people (IE vanilla), best advise is to watch your back. Know what's behind you as well as what's ahead. Don't be afraid to spam rockets at an entrance or high traffic area. For aiming, I find it easier to let the opponent jump into your crosshairs instead of trying to place them on him. Keep it steady and let them do the work for you. Every weapon has a use, fire your rockets at peoples feet to bounce them around, pull out a super shotgun to throw off someones aim. Evasion is another good one. One of the easiest things to do if someone is chasing you is while still facing forward, start backpeddling. In seeing your back facing them, most will assume you are continuing your forward momentum.