Preparation? What? Didn’t I already do all that by having a place to work and buying all these fancy tools? Sure you did. Now you’re prepared to start preparing!
Seriously though, you could just start cutting stuff off and slapping glue and paint on your models but with a little prep, it will make many parts of this hobby easier down the road and your hard work will look better and last longer.
What material your figure is made of will determine what you need do first. If it’s plastic you can start right off by removing models from the sprues (that’s the plastic “tree” all the parts are attached to). Click here for the preparation page for plastics. Metal models have an extra step that we should cover first so they can keep up with us. Go here for metals.