1. Choose the right loadouts for your gaming style. If you like to hang back and snipe away at people with a DMR, then choose something with a DMR, don't rush in with a Magnum and Armor Lock! Choose something more suited to your needs and you'll do much better in slayer.
2. Don't underestiate the usage of Armor Lock. I go into an online Slayer game with it and I can get a lot of kills. And I'm a type of guy who normally sucks online! If you're on Sword Base facing down a guy with a Rocket Launcher, Plasma Launcher, and lots of Plasma Grenades, Armor Lock is your best friend. I went online on Powerhouse against someone who always had the Gravity Hammer. Me and him were one-on-one in the little hallway under the Plasma grenades, and he was the only one in the game of 12 people who ever got the Hammer. Except for me. I went into Armor Lock as he hit me, and survived. I got out and beat him in the face with my pistol, then went into AL again as he swung a second time. I popped out and beat him, killing him and taking the hammer for myself. Soon after, he ragequitted. It was pretty satisfying.
3. Don't waste ammo on far away opponents. If you have an Assault Rifle and see someone on the other end of the map, don't start firing at him. Go for someone closer to you. If you start to spray bullets in his direction, you'll only get him with two or three of the 32 shots in your gun. And that's if he doesn't go behind cover. Try switching to a DMR or a Sniper Rifle to pick him off, or move closer and get him there.
4. Jet Pack is faster than Sprint. When you're on the Red team with a Jetpack, going for that coveted Spartan Laser in the middle of the map and see a Blue guy Sprinting for it, don't hesitate to start Jetpacking towards it! It may seem like Jetpack is slower, but it actually covers more ground, plus it can get you to some high ground if you need it. Jet for the Splaser and grab it, then shove it in Blue's face by lasering him as he runs for cover. It's never been more satisfying to see an opponent running away, then falling to the ground smoking in a flash of red. Of course, after that initial laser shot, yoou might want to find cover from Snipers.
5. Don't be afraid to get cover in the middle of a fight. Imagine this scenario: You have a DMR, running around the corner you see, what a surprise, a Red guy with a Rocket Launcher. Your initial instinct is to hold your ground and headshot him until he's dead. His is to blast you with a rocket to the face. His is simpler, but also much faster. What you could do is throw a grenade, then go back around the corner. You'll see his Rocket fly past and miss you. That's much better than dying a fast death. You could then throw another grenade and duck around the corner again to dodge his second rocket. It's pretty fun to hear a muffled explosion through the wall, see the message 'You killed FourteenBoar', then watch a body fly past and ram headfirst into a wall. Try it. You'll see.
