These tips, for the most part, are bits of advice that have been passed on to me by several seasoned online FPS gamers that I've come to find invaluable. In no way shape or form do I claim to be an authority on this matter and this list is not necessarily what makes a good online FPS gamer...
They are merely a collection of things that have made me a better shooter.
1) You are not the hero of the story: Undoubtedly the hardest thing to get used to in a online FPS is the fact that you are going to die… a LOT!! Quite often, we are SO used to being the hero of the story, and being nearly invincible in compared to the dimwitted AI soldiers, that it's hard to accept constant death. In fact, if a typical game was as hard as an online FPS, resulting in the same number of deaths… most of us would turn down the difficulty or would stop playing altogether. But on the battlefields of OFPSs, difficultly is determined by the skill and experience of the other players. Here are a couple of tricks to over coming this: 1) don't take it personally…. He/she is not stalking you… you just happened to be the one who walked into their cross hairs…. again 2). Yeah you're dead but wasn't that a great kill? Learn to appreciate the awesomeness that was your death, because next time it might be you on the happy end of that smoking barrel.
2) Economy of motion: just like in chess, you never want to move, simply for the sake of moving because unless it's the sort of game where EVERYBODY is running around like chickens with their heads cut off, everything you do should be deliberate: know where you are headed before you leave your current spot and go there!! In my opinion, if you are Oscar Mike, it should always be from cover to cover taking the time to scan for hostile movement. Standing in the open to think about where you are headed, changing your direction, run-and-gunning or simply wandering can leave you with your pants down and means that you're more likely to be the one to get surprised... and killed.
3) Aim with your feet: PC gamers often complain about having to use an analog stick as opposed to a mouse in order to aim; and while it is trickier, many of us console gamers have developed or rather perfected the art of aiming with their feet. Large, fast movements should obviously be made with the "upper body" analog but to fine tune that shot it pays to train yourself to aim with the "lower body" or movement analog. Not only will you be faster shot, but you're now also a moving target...And that means you're harder to hit.
4) Know your environment: unless you study the maps before you play (and seriously, who does that?) obviously you won't be able to know all maps inside and out right from the start. But you can ALWAYS use the immediate environment to your advantage whether it is familiar or not. For example; stick close to walls, they're your best cover - you know a wall isn't going to shoot at you ;). By staying close to walls, you movements will also be less noticeable. Also learn the maps as best as you can as soon as you can (take advantage of rounds with few people to explore and find areas you are comfortable in; good ambush points etc. Don't camp, but there's nothing wrong with favoring certain areas.
5) Check your weapon: RELOAD RELOAD RELOAD…. Would you rather get into a fire fight with a full clip or one with 5 rounds? Full clip right? Then why are you running around with 5 bullets? As SOON as you can, you should ALWAYS be reloading, sure on the odd occasion you might get caught in the reload, but it's not as likely as running out of bullets mid-fight… and then guess who's going home to mommy in a body bag?
6) Fight alone and you'll die alone: "Lone wolfing" is a common trait of new players (and some veterans ;) ) and goes back to the video game hero complex that many of us have gained from playing single player campaigns. The online battlefield is a dynamic, ever evolving environment where nothing is scripted but the background effects like crap blowing in the wind…. which makes it infinitely more lethal than your average single-player VG battlefield where after a few run throughs, you know where and when to expect exactly how many guys to pop out. So how do you protect yourself in an environment that has an ever evolving front line? You find a buddy and you stick with him!!! How many times have you been caught off guard and panicked (even if slightly) when you realize that the one target you're about to shoot is actually two, no wait, three contacts emerging from a tree line? The split second of indecision it takes to assess the situation (which one do you shoot?) can make the difference of being riddled with holes… or being the one doing the riddling….. Furthermore, most games provide the ability to customize your load out which means two players can take kits that complement each other… and you should!!! There is strenght in numbers. unless it is straight up deathmatch, then there's mass blood shed in numbers :P
7) Panic button = melée. Every FPS I've played has a melée attack and whether its a knife strike or the butt of your rifle, it is lethal in every game!!! And yes, it sure is fun to sneak up and knife the guy too busy looking out a window to watch his own back but the melée attack can, with practice, become an incredibly effective panic button too! For example, you are Oscar Mike from where ever to where ever, and as you round the corner or break down a door, you suddenly come face to face with another player, in a panic you start to shoot but if you had have just meleed you'd already be on your marry way looking for your next tango.
8) Target assessment (or crowd control): it's like Kenny Rogers says "you gotta know when to hold em, know when to fold em"; the name of the game is "shoot the red guys" which seems pretty straight forward. But is it really? Firing at absolutely every contact you see, MIGHT get you a boat load of kills, but more likely it's going to prematurely give away your position to all the wrong people, not to mention the fact that the guy you just nicked with one bullet out of 30... Knows where you are, has a full clip, AND now has a grudge while you... have to reload. The moral here is this: generally don't shoot unless you "know" you can kill your target. "Target Assessment" also includes learning to quickly prioratize your targets; decidng which target to shoot at first of a group is critical to survival when you're out numbered!! This generally, is done by deciding who is, or is going to be, the biggest threat to you the soonest. Obviously guys/gals that see you need to go down the quickest. But what if they don't see you? If you can see their Rank or Level, Higher-ups/Officers should be high on the list of "first to die"(they're probably the better players). And if the game includes classes, Medics should also be high on the list (if they die, nobody's coming back). Ultimately however, target assessment isn't black and white; its very situational and largely comes with experience but basically try to think like a "real" soldier and you will find yourself playing signifcantly better.
9) Are you the hunter or the hunted? As the predators we are, one of our primary means of identifying targets is through motion and as general rule; if it moves... Shoot it!!! This may seem obvious and in a sense it is but what does that really mean in the OFPS gaming world? It means if you don't need to move... Don't. By this I don't encourage camping but I do suggest your movements be slow and deliberate; I've spotted and dropped countless dudes because they were jumping around, or flailing about when if they had have just hunkered down and sat still I wouldn't have seen them and they'd still be alive! It's also much easier to spot contacts through their motions, when you aren't moving.
10) Watch and learn: dead? Don't worry because most games let you watch a kill cam... Which you should because that guy/girl did something right and survived while you're taking dirt naps. By watching kill cams or even just watching what your squad mates do (especially the more seasoned players) you'll see little tricks that you might not otherwise think of but most importantly, you'll start to see what you did wrong and why you came out on the losin end.