Some beginners advice if you do start on Photoshop: avoid use of generic filters by slapping them over everything you do and think to yourself that they look great because you've just discovered them for the first time. They don't look good and they are a dead give away. The craquelure filter is an amateur's favourite for some mad reason, and I was guilty of using it a few times myself. Composition is more important if you're putting together something completely from scratch, so think about that more than the actual program itself and the tricks it can produce. If you want to produce some nice professional-looking things, then start learning masking and gradient tools first, as those are the essential things needed to get things blending. Also, don't neglect colour grading and values when splicing images together. Everything has to seat into the scene as if it belongs there, so practice that too.
Oh, and one of the things about diving into a new application is that when you first open it up, you'll be instantly intimidated by all the options and such. Don't let that throw you off. It's perfectly natural. The basics are all you need so learn those first, and most of the time, the basics aren't really the basics at all, but essentially very powerful tools that you'll use the most. PS can be a very simple, yet deep program to use if you need it to be.