It's tough to able to make it as full-time, professional illustrator. Most people have another job and do as much freelance work on the side as they can. There are a few who steadily increase their freelance work and eventually transition into full-time work, but that's rare.
Check out the Society of Illustrators, they have lots of competitions and publications every year and can be a good networking tool and resource as well.
Check out the Society of Illustrators, they have lots of competitions and publications every year and can be a good networking tool and resource as well.