I agree with Digidog, the tripod is the most important thing. I must be getting old and shaky because I get blur sometimes at 1/125. I have to go to 1/250th of a second to ensure crisp handheld shots. In low light that just isn't always possible.
I always start in Manual mode and adjust to 0 on the exposure meter. Depending on the shot, I will be interested in a certain shutter speed (like handheld medium light) or aperture setting (where DPF is important). I adjust the primary first then the secondary. In extreme cases I may have to adjust the ISO or turn on the ND filter to get the range I need.
After I set in Manual, if I need to take quick shots, I will switch to either Av or Tv. The main thing is to set the primary parameter and ensure the secondary has enough range to be able to adjust to different light. For instance, if I set the shutter at 1/400 and then need to set the aperture at 2.0 to get a 0 meter reading, I will run into trouble when I set to Tv because the aperture has run out of range and if I focus on a darker spot it can't adjust any more.
Remember, in Av or Tv, exposure is a SETTING. in M exposure is a READING.
Another note: for normal indoor photography, you might as well use Program mode. If you do (with onboard or external flash), you will notice the camera will select 1/60th for the shutter speed and adjust the aperture accordingly. I've been told 1/60th is the right speed to sync with the flash. Unless you are trying for an effect, either use P or Tv at 1/60th, which is the same thing. The camera manufacturers can't be all wrong. Since I've done that, I've had much better success with flash photography (420ex doesn't hurt)
One other thing about white balance and RAW. Apparently white balance is a post shot thing that is done in the software. In the RawShooter Essentials manual it suggests you just set the white balance to AWB and adjust in RSE. I've dont that and rarely have to adjust it.
Does any of that make sense?