The right way to play video games

1) Learn enemy mob patterns
2) Observe your environment and use them to outmanoeuvre enemies
3) Simplify your attack plan first. Only knife. Only pistol. One shot at a time.
4) Put it all together

5) Quickly memorize controls
6) Use powerups only when really necessary. Do not rely on them.

7) Put everything together, from 1) to 7). What you have, is a master of the battlefile.