Try to keep textures scaled at 1.00 as much as possible. this is the default scale anyway, so just don't change it, unless you're making large outdoor areas (in which case you should make things like rocks or dirt 2.00.)
Something you might also notice is that if you clip a wall at an angle, or use vertex manipulation to get it that way, it will stretch the texture out a lot. There are several ways to fix this, but a good bet would be to open the texture application tool, select the stretched face, and check the "face" box.