Keep in mind that Photoshop isn't the end-all, be-all of art programs out there. I use it, and I love it, but I also freelance graphical work, and do graphical work at my day job.
But, it's also very expensive, and designed with the professional in mind. It's primary purpose is also just what its name implies: manipulating photos, although it does a bang-up job in other graphical tasks.
But, there are less expensive alternatives. For example, Corel Painter is FANTASTIC for illustrative artwork. It does its best to mimic the results of traditional media, too, and excels at it.
-- BK