keep in mind that ken rockwell is an arrogant idiot. but he takes great pictures. there you will find some of his guidelines.
http://www.kenrockwell.com/tech.htm
on this site, you'll get guidelines for lots of commerical type shots, and on the left some more. if you click the link "back to the main site" there is a tutorials section with several sub sections, and many articles explaining various facets of digital cameras and guidelines for taking pictures.
http://irphotoschool.com/
is it possible for you at all to take a free course or something somewhere?
i found that once i learned about the basics of aperture, shutter speed, light metering and framing, theres not much else one can learn from anyone, aside from technical stuff like taking some really cool portraits w/ the shallow DoF effects (sharp face, blurry vackground).
so the best way to get better is just taking lots and lots of pictures on your own, and w/ the digitals its easy to get better, as you see the results right away and you can immediately change some settings and take other shots until you get what you wanted.
also, read the manual. the camera itself is a tool (of course), and each digi cam is different, you need to learn your camera in order to get good results. if there are things about it you dont like, you need to be able to compensate. you wanna focus on an off center object? check if your camera allows that etc.
oh and last but not least, an very important part of digital pictures is post processing and touching it up. before i ignored this, but really just by changing a few contrast, brightness and color saturation settings, you can make your regular shots look MUCH better. if the tech is there, why not use it?
when i developed film, i selected my exposure time and the contrast, so I altered the development process till i got the results that i wanted. post processing is very similar IMO. its just that when you take your film to the local store, they put it inside a machine with generic settings for overall "best" quality, and it automatically develops the films according to those settings. any photographer that develops his own films fools around with each shot, trying out the best exposure times, lighting etc.
post processing is no different, use it to your advantage.
you can ask me a few questions if you like, im not sure i'd be able to answer them, as im a newbe, but ill try. but there are some great phtographers here, like sporsk, who may help you out as well.