Advice and instructions taken from actual military sources.  Some of these guys must have had a sense of humor

"Aim towards the enemy."
--Instruction printed on U.S. Rocket Launcher

"When the pin is pulled, Mr. Grenade is not our friend."
--U.S. Marine Corps

 "Cluster bombing from B-52s is very, very accurate. The bombs are guaranteed to always hit the ground."
--USAF Ammo Troop

 "If the enemy is in range, so are you."
--Infantry Journal

 "A slipping gear could let your m203 grenade launcher fire when you least expect it. That would make you quite unpopular in what's left of your unit."
--Army's magazine of prevention maintenance

 "It is generally inadvisable to eject directly over the area you just bombed."
--U.S. Air Force manual

 "Try to look unimportant; the enemy may be low on ammo."
--Infantry Journal

 "Tracers work both ways."
--U.S. Army Ordnance

 "Five-second fuses only last three seconds."
--Infantry Journal

 "Bravery is being the only one who knows you're afraid."
--David Hackworth

 "If your attack is going too well, you're walking into an ambush."
--Infantry Journal

 "No combat-ready unit has ever passed inspection."
--Joe Gay

 "Any ship can be a minesweeper....once."
--Anon

"Never tell the platoon sergeant you have nothing to do."
--Unknown Marine Recruit

"Don't draw fire; it irritates the people around you."
--Infantry Journal

"If you see a bomb technician running, try to keep up with him."
--USAF Ammo Troop