1. Battle Rifle and Power Drain, throw power drain, shoot at head once, enemy is dead.
2. If your using a gun and come across an enemy using a shotgun/sword, backpedal and shoot, throw grenades if you have any.
3. Never use the sniper rifle unless you have your back to a wall or a group of friendlies. You will be blind sided, and if you do, just use it then get out of the scope quickly to make sure your safe.
4. If low on ammo, a charged plasma pistol shot followed by a melle is just as good as any mauler.
5. Plasma pistol charged shots disable vehicles. If your in a big map like valhalla I think its called, always carry one if you can't get your hands on the better anti vehicle weapons.
6. Power Drains also stop vehicles.
7. Everyone has their weapon, it can be anything, even something like the plasma rifle which most ppl dislike. But there's always one weapon you will like and prefer above all others and normally excel above others using weapons of the same caliber when using this weapon. Find the weapon for you and keep one with you whenever you can, its always good to have an advantage even if its just a psychological advantage. Mine for instance is the battle rifle, I can beat any sniper with my BR and some decent cover hopping.
8. Tanks...if your using a tank stay far away, tanks should be used as artillery from a distance, a close tank is a dead tank, they are too slow to avoid any anti vehicular weapon. The only time to get close with one is if its in your interests to be a distraction then its perfectly alright to do so.
9. Ghosts, their weak point is the "wing" get a spike grenade on the wing and the ghost is gone.
10. If your going to hijack something other than a tank, knock down their shields with grenades/guns on the way to the vehicle, then when you hijack the vehicle the knocking off damage from you throwing them out will kill them.
11. If using a rocket launcher, aim for the ground near where the person is standing...never at the person.
12. Grenades are the most damaging and plentiful weapon in the ENTIRE GAME and if you can master grenade trajectory (know how high to throw a grenade to hit someone halfway across the map) you will gain a HUGE advantage. The other huge thing is knowing WHEN to use grenades, grenades are tricky, the time it takes to throw a grenade can give your enemy those extra few rounds in your torso that give him the win, so make sure your grenades hit. Play with friends and work on your grenade skills, I can throw a sticky grenade from the beach in high ground and hit the spartan laser on top of the building, its all about trajectory, grenades can really even the odds against snipers. Toss frags around corners or into small rooms, frags are very easy to find so there's no reason not to. See 2 ppl battling it out? This is war, don't feel bad for being an a hole. Throw a frag in the middle of them for 2 free kills.

I'll update this as I think of more to add to it, I know these aren't "pro tips" or anything but someone might find them usefull.

1. Whenever you play swat, ALWAYS keep the reticule head-height. Practice walking around the maps beforehand getting to know the lay of the land. You will almost always get the kill if you come around a corner and your already aiming at the other guys head.

2. Just my opinion, but the Character type doesn't matter either. There the myth that playing as an Elite in SWAT raises your chances of survival, and makes you harder to hit. I personally have never had any problem killing Covies from across the map. And a Spartan player who made it to 40 cant be THAT easy to kill can i?

PS, I got a triple splatter kill with a ghost last free for all match, pwnt.

Thats usually not the best idea, as the map is mostly mid to long range

In my personal opinion, having one short ranged weapon and one longed range weapon usually gives you a strong chance...

It provides excellent short to long range covering fire, and after you empty a magazine into your enemy, you have either killed them or maneuvered close enough to punch them in the face with your energy fist...

I always use my BR, shoot them in the HEAD 3 TIMES, beat down, and they don't die.

Like 2 shots of the AR, 1 beat down, and I am down.

WTF!

I'm a noob.