This is how I do texturing, and it always works for me:
1. Select the part of the model I want to texture
2. Press "a"
3. Draw a rectangle around the area I want to texture
4. Right mouse click inside the rectangle I just drew and load texture
5. Fine tune the texture area to best fit the area I want to texture
6. Press "a" again
7. Press "b"
The texture should now be applied to the model.
-Pilot