Blow those propane tanks up before your enemies use them against you.
Whoever holds the warehouse controls the flow of the game, so try to hold the warehouse if possible.
Hiding under stairs in this level is sneaky and effective. You can unload many a round into a man's back before he has any idea you're under there.
Wall hacking (firing through walls) works really well in this level, use it and beware of it.
Make sure you have Recon for this map.
Watch out for grenades and other explosives upon entering or exiting the warehouse. LAWs are also used quite often in there, so be careful.
It's possible to get up on top of the ground-floor entrances/exits to the warehouse (on the outside). This means if you're standing up there you can shoot people in the head and back as they come running out.
Make use of cover, lots of Snipers in this level.