HD Planes / Textures

[The chaser]

Also, one thing I forgot to mention: Try to make the textures tileable since the moment you make the photo. I'm even making some photographs to stuff to improve my skills.

If I was you, I'd try first to make photographs of artificial things (a wall of your house, or the street floor, some building bricks, etc) so you get practice with more-or-less easy textures. Nature is a real challenge to make in a game, so try first with something simplier (like the bricks) and, when you have the experience, photograph nature.

Making the pics excellent already with the camera will save a lot of time, as you won't have to be bitching in programs. (It isn't bad, it just consumes time).