You spawn with a centcom survival kit in your backpack or satchel, which includes an emergency oxygen tank. It's a decent emergency weapon, and can be used to break down windows.
If you're outnumbered, remember that knocked down or knocked out isn't dead, don't count an enemy out until he's gasping.
Screwdrivers can be used to stab eyes if there is nothing on the target's head/eyes/face, four good stabs will make them drop whatever they're holding, a few more will make them permanently blind.
If you don't have the power to stun, keep moving and try to force your opponent into a narrow area where they can't avoid your attacks.
If you CAN stun, use corners to your advantage to force them in close, stun them, and grab them three times to strangle them.
When all else fails, using the disarm intent with an open hand has a chance to knock someone down, givng you three or four uninterrupted hits.
Punching is absolutely useless against armor or helmets.
Rolling pins do no damage, they just cloud vision and piss your target off.
Metal rods can be found in primary tool storage or broken off of grilles and windows. They do great damage and are relatively easy to acquire.
Space helmets, welding masks, and sunglasses block flashes. Flashes work very well against cyborgs, who can then be buckled to chairs and rendered helpless. You can find flashes in security, the CE's locker, robotics, tech storage, and the bridge.