Tips on texturing?

Ok so my models look SO crappy compared to other peoples! But it isnt because the mesh, i have to say that my meshes look great. The reason they look so crappy is because of the textures. So im asking you guys for tips on texturing. Like the image below, where do people get textures like this? Because i know they dont create them from scratch

It looks like there is some high poly to low poly normals baking going on there. Do you know how to UV map? if so, you can make these type of textures, by making a high poly detailed replica of your game mesh, sculpt and edit it, until it looks good, then bake the normals onto the UVs of your game mesh. You can also bake other things, like ambient occlusion.

Actually I have never baked beforeā€¦ well not textures like that. Do you know a good tutorial or something that does it?