If you're not a fan of landscapes then you could try making accessories for your characters. Could start with some simple boxes, bags, pendants, armor, helmets, glasses, weapons, tools, and so on. You could show how they function if they have any moving parts maybe. Just a thought.
I like 'Sketch Book' for drawing perspective as it's got loads of great tools for perspective drawing that work very similar to real-life tools (*Sketch Book App is free, Sketch Book pro is payed).