Engineer Kit Weapons
The engineer's weapon of choice is the SMG. This rapid-firing weapon excels at close range, but is severely limited at longer distances. Remember this when you're moving across a map. Stay close to cover, this way any enemies you encounter will be on your terms.
You will not win a long-range battle with a sniper, and even the assault and medic kits have longer range weapons than you do. Unlocking the red dot and 4X scopes for your SMG can increase your effective range, but in general it's best to do all you can to ensure you face enemies in close proximity.
Up close, though, no kit can pour as much lead into a foe as the Engineer. All SMGs deliver a lot of bullets very quickly, but there are subtle differences between them.
Some, like the UMP and the SCAR-L, deliver approximately 600 rounds per minute while others, including the UZI and PP-2000, deliver nearly twice as many. The key difference here is the damage of individual bullets. The rapid firing guns tend to do less damage per bullet, but make up for it by delivering far more lead.
Deciding which weapon to use comes down to your personal style. Do you have the discipline to fire in short bursts, delivering only enough bullets to take down your target, or do you subscribe more to the "spray and pray" school? Those who fire indiscriminately with a PP-2000 are going to find themselves spending more time reloading than killing, so that's something to consider when choosing a gun.
As far as backup weapons, the tracer dart pistol is a fantastic choice for an engineer. You will constantly be finding yourself near vehicles, both enemy and friendly, and being able to tag them before firing off an anti-tank round can make a huge difference in your accuracy and effectiveness.
Check out page two for more Engineer hints and tips, including repair and destruction, effective use of the RPG and Anti-Tank Mines, and Rush Mode advanced tactics.