Emisary

Best answer as chosen by Asker / Ratings
First of all find a good spot to hide after the lazer designater locks on, secondly you have to use the right control stick to guide it. Try to guess where the enemy vehicle will go next and guide it there. Also try locking onto a vehicle and hitting a different one, they never see it coming :).(P.S. If you get a chance, try to hit a helicopter, harder than heck but if you do you get an achievment). It takes some getting used to but in the end you will be public enemy numero uno. Also watch out after you lock on, you light up like a flare on the enemy teams radar, at least to the tank or vehicle you locked onto.
Good luck Lone wolf of the battlefield....You'll need it.