[Hawiian Cadder]

Inventor has some good tutorials, better than solid works, so without a teacher it is probably easier to learn, If you want more practice, what I like to do is CAD unique solutions to older FRC games. read about a few good robots from a prior game and then design a better one.

As for choosing between solid works and inventor, I think solid works allows for faster Modeling, and more efficient use of time, however Inventor makes AWESOME renders, and the FEA in inventor blows the analysis tools in solid works out of the water. The file management and virtual parts in solid works are excellent, and again allow much faster development.