If you can't go to art school you make your own art school. You make your school by constantly studying not only art that you like but the best that the past has to offer. You apply what you've learned by drawing every day for as much time as you can. If you're serious about growing as an artist then give it the time it needs. If you want to learn then spend what you can afford on quality study materials. In my opinion the best materials are the ones that stress the fundamentals of construction, proportion, anatomy and perspective. If you don't look at reality then how can you exaggerate well? Don't be put off by the age of some of these or the fact that they don't resemble comic books or manga/anime. As the great Alex Toth once said: "use it all, sift it all and assess it all".