Properly UV Map Textures

Support Materials and Textures
#1

I have been learning blender and I have always had a problem while UV mapping textures. The texture always comes out good on simple objects but sometimes the texture appears on the other side of a face instead of the side in which the rest of the texture is textured.

Texture Problem.png850×479 213 KB

How do I fix this?

#2

Select the face and W / Flip Normals

Ctrl+N recalculates normals for selected faces