Make sure you take a BAP on all lrm mechs and try to stay close to friendly lrm carriers, but at least 180m away. That way, if they have a BAP, which they really should, you can cover each other if an ECM light tries to get close and take you out.
Also save up for another XL engine. Catapults take them really well due to the tiny side torso. The weight savings could mean that you can equip jump jets and more ammo if you have the room.