If you don't like reading, watch my short 3 minute video. Everything is easy and explained there.
This is an easy game to 100%.

Simply clear level 1 of enemies, then, as long as you are playing the game, and it isnt paused, you will get achievements. No kill count, no jumping nonsense, just be in the game. Simple.

Note: UFO's on the minimap can kill you, so just make sure you dodge their beams, and you'll be fine.

Game takes about an hour to get all 3222 achievements, so have fun!