Also its important to realize that using photos in your textures is not wrong. In fact its quite possible to make great textures using nothing but slightly modified photos. The problem is that most noobs take something like a photo of a car, slap it an a box and call it a model. This results in a model of very low quality. Here are the steps I use when preparing a texture from a photo:
1. I always start with as high a resolution photo I can. This way I have the opportunity to do a lot of cropping and still end up with a high-res texture.
2. First I rotate the photo so that it's lined up correctly and isn't crooked. This is especially important when you have textures like bricks that have a lot of horizontal and vertical lines. I also remove any lens distortion or correct any perspective.
3. Then I remove any lighting that's apparent in the photo. Any shadows, glares, or evidence of camera flash.
4. If the photo is of something like rocks or wallpaper that needs to be tiled, I make it seamless.
5. If the photo is lacking contrast, isn't saturated enough, etc. I edit that to my liking.
6. If the photo is missing colors I want in it or has colors in it that I don't want I remove them/add them.
7. At this point the texture no longer looks much like a photo, and I do some final touch-ups; I sharpen it a bit, apply any subtle filters that I think are fitting, and then I'm done.
If you do something along the lines of those steps you should end up with a fairly good texture. Obviously you shouldn't just slap this on a model. It needs to be edited depending on how it will be used. Sometimes you'll need to edit the shading on it, sometimes you'll need to warp it a little, etc.
Hope that helps.
i like orange
