Reddit reviews Photography (11th Edition)

http://www.amazon.com/Photography-11th-Barbara-London/dp/0205933807/

This what they use as textbook in college photography courses. Get used one or earlier edition on eBay to save some money.

This is the textbook we were told to get Last year when I started school for photography, its an excellent reference tool and will give you a basic understanding of light, design, composition, and colour theory (http://www.amazon.ca/Photography-11th-Barbara-London/dp/0205933807/ref=sr_1_2?s=books&ie=UTF8&qid=1408949706&sr=1-2&keywords=Photography+textbook).

The best thing you could do is to hook up with a local commercial photographer and assist or shadow them, maybe take a night school course at a local Community College or University. Understanding light and design is paramount to making it as a commercial photographer IMO, its what really separates you from every other guy with a DSLR.

I'm not a commercial photographer, I shoot music (events) and promos for some Toronto based publications and i've built some working relationships with some commercial photographers. This is just my personal opinion.

TL;DR Read books on design (design in painting and sculpting and graphic design are interchangeable), colour theory, and pay attention to detail; study images from magazines, breakdown the lighting. Keep asking questions, the technical aspects are just as important as having strong marketing and business skills.

Edit: Book on design (http://www.amazon.ca/Basics-Creative-Photography-Design-Principles/dp/2940411360/ref=sr_1_2?s=books&ie=UTF8&qid=1408950177&sr=1-2&keywords=Photography+design+textbook)

https://www.amazon.com/Photography-11th-Barbara-London/dp/0205933807