Some books for you, (in order of merit IMHO)
How to Cheat at Photoshop CS5
Art & Design with Photoshop
Creative Photoshop CS4
The Art of Photoshop
Get a flickr account, and participate in these groups:
Get chatting to the people in the above groups. There some talented people there, and they are friendly and helpful.
A list of tutorials which would suit what you are trying to do
Participate in the How To Cheat at Photoshop forum. Steve Caplin is a regular poster, and about as clever as it gets when it comes to Illustration with Photoshop.
Of the above, I'd list How to Cheat at Photoshop as a must have because it gives you the building blocks to create and realize your ideas. 100% Photoshop does the same to a lesser extent, but is a LOT of fun to work through.
Best thing I can tell you is Practice, practice, practice. Find an object and try to recreate it the best you can and move on to another object and so on. Get the time in. Using references is not cheating, no matter what anyone tells you. It how you learn. The more you recreate an object the easier it is to picture in your mind what it should look like and be able to see that object while you create it.
Are you having issues with Ps in creating your ideas (tool problem) or problem with not having ideas to crete results in Ps (mind problem)?
People here best equipped to help you resolve a tool problem.
If a "mind" problem, seek resources on being more creative: books, videos, ideas from www.
Even the best designers and book writers have mental "blocks" for some period of time.