Having been modeling now for almost 3 years, I see a lot of new photographers, models and MUAs join a site like MM and get discouraged right away. Some of them even want to leave after a few days, not even giving it a week.
Now, sure, it’s pretty easy to get discouraged. Joining a site like MM, OMP, or any of the various other modeling comunities online doesn’t mean the work will suddenly start rolling in. And if it does, it likely won’t be paid work.
The work won’t just start rolling in, because networking sites require a lot of work. I’m on 4 or 5 modeling sites, and the ones I get work from? The ones I spend more time on.
You have to get your name out there, and show people that you exist.