Really depends on your play style. I myself prefer to hang back to snipe from afar, or go in a vehicle to get kills to clear the way for CQC type players.
If you're a close player, I would think having a Assault Rifle with a Magnum in your primary load-out, with that have a plasma grenade and Promethean vision. You're be a danger to all CQC players with that load-out. because of the ease to spot close opposition.
For medium have a Assault Rifle and Battle Rifle, OR Carbine with Battle Rifle. I'd use a frag grenade and a regeneration field or thruster pack with it. Try and stay in corridors with those load-outs because of the damage you'll deal with a quick frag and a BR/Carbine shot. The AR is useful to do damage if someone gets too close for comfort.
For long distance play styles (which I mainly am) use a DMR and BR, OR a DMR with Light Rifle combo. With that, you'll destroy players from across the map as the DMR and LR are very powerful the further they get from the opposition. Also try use active camo for protection from people with snipers.
I don't recommend doing the play style of jump everywhere. Not only doesn't it work that well, because of aim. It wastes time if you keep hitting your head against the ceiling, invalidating the point of jumping. I do though recommend strafing left to right a good portion of the time. Of course you don't really need to when you're far, but up close it's a must.
Also, if you are a vehicle user, try and use the bigger machines. (ie) the Wraith, Scorpion, Banshee and Mantis. And even the Guass Hog. These will boost your score in the end. Though some may not be the greatest of using these at the start, with a matter of time you'll be getting frenzies with them.
Finally have a back up load-out. Something that you can depend on when your main style isn't working. Example. When my DMR/BR combo doesn't work (which it almost always does) I tend to use my LR and plasma pistol combo. Easy to get kills medium-close with that combo. And it destroys vehicles too.
Hope this helps!