You must be on the Republic side and either get on the big turrets or become a Heavy Trooper. There is an gigantic chance that there will be a steady flow of Droid Tanks and STAP swarms. Not much risk but the Shock Cannon is a thing to be careful of.
This is a prime level to earn the Demolition medal. If you can get the Guardian and War Hero medals, you will have no difficulty with staying alive while you can easily nail the critical point on the Armored Tank Droids as they approach the Sea Wall (it is the smaller of the two cylinders; the rear one, around which the tread is threaded). Due to the speed of the droids and their tendency to turn unexpectedly, you will want to get close for the shots you take.