You never want to the friend/mentor/pet of the hero in a martial arts movie. You will die or be beaten so badly you'll wish you were dead. This will inspire the sweat filled work out scene before the triumphant return, however. This was even done in the movie Ring of Steel which was a cage fighting type movie done with swords. The hero was an Olympic fencer. Great sword play in that one.

The hero will never be able to defeat the final bad guy through strength or skill alone. Instead, he uses quick wits or gimmicks, such as throwing a bit of chain at a leaking propane tank to cause a spark and blow up the bad guy. The Perfect Weapon, or get the bad guy in a spot where he gets electrocuted by the third rail of the train in Chicago, then gets hit by a train. Rapid Fire.

No matter how bad things seem, the answer can be found in a flashback.

Semi auto pistols do not click when they run out of bullets. The slide locks back and the hammer cannot fall. The only kind that do that are broken.

Save the dog! No, don't save the dog. Okay once. But the second time the dog leaps out of the truck in the middle of the lava flow, evoke the Darwin rule. We had a movie critic that was inspired by Dante's Peak to award a 1/2 star bonus to any film where the dog died.

An untrained person with a submachine gun will never hit a friendly. King Kong (remake), I, Robot.

Tom Cruise plays a cocky, young guy. (Thanks to the Amazing Jonathan for that one)

For a movie that had a character that was developed well, then was killed at a really unusual time, Deep Blue Sea. It was basically the step of the curb and get hit by a bus thing.

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A Nerd can figure out how long it will take the original Enterprise traveling at warp 6.5 to travel from Regulus to Antares.
A Geek with think he can use that to pick up a girl in a bar.
A Dork knows he can't pick up the girl with it, but will hang around for hours anyway, just in case she asks.
She might. You never know.