There are some useful sources on internet to learn about Graphic design even Blogs. But also is important some advices that will be mentioned bellow
Graphic designers must have some skills and talents to adapt the demands of businesses such as : career training, proficiency, expertise and knowledge; all of them you can acquire in a good specialized school. Later, the training will come when you get a job, perhaps as an intern to begin.
Likewise attributes of a person in terms of work ethic, teamwork skills, creative thinking and positive personality traits are needed to be a successful designer
Understand the basic fundamentals of art (like line,shape,texture,scale,etc.) is essential in order to become as a good graphic designer
Develop also the following skills : project management, typography, photography
Knowing about Web Design, Social Networking and Communication will be keys to help you to become a successful designer.