Holding up a fist will instantly stop an entire army dead in their tracks.
Any time bullets are shot at you in slow motion, you can avoid them (in slow motion) by leaning way back until your spine is almost broken. Hover in this position for several seconds until the bullet-time effect has ended.
Make a ‘V’ with your index and middle finger. Now point them at your eyes, then your fellow soldiers’ eyes. This alerts them to use vision instead of their sense of smell to navigate streets and tunnels.
The enemy can’t smell lit cigars due to their inferior, foreign senses, so by all means, smoke up!
After you’ve used up your clip, you can safely throw your weapon to the ground in favor of a handgun. The army doesn’t mind you throwing away M16s. They have thousands more laying about.
Covering oneself in mud will drop the body temperature enough to fool aliens and thermographic registers, but won’t cause hydrothermia.