There are a lot of good tutorial sites outside of the digital scrap community.
One site I like is Bio Rust. They have a lot of good tutorials on the basics of
using PS but they also have some great ones on creating textures and special effects.
RNEL has an unbelievable number of tutorials from basic to advanced. You can learn
how to create everything from lightening to frozen text. It would take days to work
through all of them. Many might not directly apply to scrapbooking but they will demonstrate
the things that you can do with PS and in the process inspire you to try different things.