You should distinguish between design skills and tool skills in your quest for learning. To draw the parallel with the technology world - knowing IDE well does not make you a good programmer nor computer scientist. So being skilled with Photoshop or Illustrator won't make you a good designer.

In my opinion the good introduction to basics of graphic design 'seeing' would be this book: http://www.amazon.com/Graphic-Design-The-New-Basics/dp/15689...

It's essentially like Graphic Design 101 the modern way. It would be a good start towards more specialized learning towards interface design, user experience design, information design or data visualization disciplines.