So, you want to join the GM4 Public server? Well of course you do.
First of all, you need to fill in the form at gm4.co/#join.
Fill in the entire form
Some people just enter their IGN and e-mail adress. This is not enough. Make sure you enter something in every box. If you don't, the chance you'll get accepted is very small.
Write your IGN correctly. Make sure there aren't any spaces before and after your name. Spelling the rest of the form correctly will help, but isn't everything.
Do not apply multiple times
This won't increase your chances of being accepted and will just waste time. It might even reduce your chances.