Can anyone give me some indoor photography tips?

I really like taking outdoor pictures with natural light, but right now it is the middle of winter with over a foot of snow outside so that is not really an option, especailly for portraits. I can never seem to get indoor pictures to turn out right. I usually turn on a lot of lights in the house but still the pictures look bad. I don't like using the flash because that washes out the pictures. I have a camera with manual modes. I also have a tripod. Any suggestions?? What camera settings should I use?? Thanks!!