Well, from my experience, it's better to make games in teams, since almost nobody by his own can master all the aspects the game making involves p.e. design, spriting, music and sfx.
There's a little community of game makers that i frequent,
www.gmclans.com , and what we do is make games in teams, named clans. We have all kind of skilled people there, from designers to musicians, including programmers and pixellers of course.
Sorry if this sound like a promotion, but that is the only place i known that really can help you to get into gamemaker.
You can try to make games alone though, just do what we said, start with smaller projects, and document yourself in every aspects of the Game Design.
Good luck with your search