You want something with at least both A (aperture priority) and M (full manual) modes, and with the ability to do both spot metering and averaging. Autofocus is handy, but make sure you can override it manually without a bunch of hassle. Choice of lens doesn't matter hugely except that the cheaper kit lenses are often so bad that they can drive you away from photography. By all means, keep the cheap crap lens that comes with your cheap secondhand camera, but also spend $50 to get a good 50mm f/1.7 lens - it will be razor sharp, you can get nice shallow depth of field and it will teach you to move the camera around for composition.

Though this is APUG and it will piss off some people here, the fastest way to learn is to buy a cheap secondhand DSLR ($200?) and go shoot about 10,000 photos on it. The instant feedback is invaluable; ignore anyone who never had that and says you can do without - of course you can do without but it doesn't make it a good idea. Once you know what you're doing with metering and composition and can say with absolute confidence that pushing the shutter button will result not only in a technically good (properly focused and exposed) image but one worth keeping, then come back to film. Get a nice medium format camera or whatever and enjoy a huge step up in technical quality over what you can get from affordable (under $10k) digital systems.

Once you have a basic camera and one good lens, the biggest difference in quality (much more important than ANY body feature or special lens) you can make is off-camera lighting. A cheap wireless flash that you can bounce off walls/ceilings makes a huge difference.