I recommend Adobe Photoshop or Illustrator for graphics. If you are a student in the School of Media and Public Affairs the Adobe Creative Cloud is available for free. If you go to another school check and see what deals your school has, a lot of schools offer free or reduced prices on Adobe Creative Suite software.
Here are some great tutorials for Adobe Photoshop and Illustrator.
Some great free and online and far simpler tools:
Further resources for infographics:
The Noun Project (my favorite resource for icons and images, just make sure you source them!)