C++ for dummies is a personal favorite. If you fully understand the syntax and how to implement it (classes, inheritance, templates, namespaces, etc etc), I'd recommend looking into GUIs (Windows/(other OS) programming, graphics libraries (SDL, SFML, OpenGL, allegro), QT kinda falls under both so it's a good place to start. Also it's always handy to get more math (you can never go wrong with more math).