I would recommend the book by George Barr, Take Your Photography to the Next Level. It covers a lot of artistic end of things without being too overbearing. He kind of gets a bit guru-ish, and a tad bit pretentious in places, but the advice is nonetheless pretty solid.
Figure out who your favorite photographers are, look at a very wide selection of photographers from a variety of eras. REALLY look, try to appreciate all of them. Often times the most inspiration can come from the photographers who make images that are sort of hard to appreciate, don't get sucked into eye candy, try to understand why these photographers are held in such high regard, especially if you don't immediately understand why. It's easy to appreciate Ansel Adams, but there is a subtly to Elliot Porter that is a bit harder to see.
From here it's vital you don't end up an idolizer. You don't want to get into just into just making cheap copies of your favorite photographer's work, create images that represent your world view. Immediately forget your favorite photographers and make your own images, focusing on themes that are important to you.
Analyze your own work, try to understand what you saw and why you saw it. From this intentions are formed which are taken back out with you and solidify into a theme. But do this only after you've completed the image. While you're out, shoot intuitively, listen for those cues that tell you that an image is nearby, and look very, very carefully for what you subconsciously know is there. Go over every inch of the area. It's like playing "hot or cold", try to feel the image out, rather than trying to force something great.
Listen to the "pros" but understand they're mostly talentless hacks, they have good advice - especially regarding the technical end, but for the most part these guys are glory hounds that will shoot only to appeal to aesthetic titillation, they know what sells and that's all they tend to be about. Still, though, to accomplish this they require a solid understanding of the technical end of things, so don't discredit them entirely. Of course, if you want to be a professional photographer understanding all these aspects is vital to being successful. If you're on the starving artist program, take what they say with a grain of salt.
Then again, maybe you don't want to listen to me at all. People seem to think my stuff sucks.