There is a bit of a trick to applying flocking. While most suppliers will recommend applying over wet paint or glue, this is not a good practice because if you mess up you'll ruin your part. Your best bet is as follows: first make a mix of 50% water and 50% white glue. Then add just a drop of dish soap to the solution.

This is important, as it is the "secret ingredient" to making your flocking come out evenly. Apply the mix where you want your flocking to be. While still wet, sprinkle the flocking on evenly and lightly press it down to seat it in the wet glue. When dry simply tap the model lightly to remove excess flocking. If you'd like it to be a heavier covering, simply apply the same mix of glue over the first and add another layer of flocking.