Like most people these days I take my camera with me everywhere. You just never know when you’ll find a great reference whether it be a texture, color, material, whatever. Nothing beats great reference material. If you shoot it yourself you’ll notice the smaller details even more. The best way to recreate something from the real world is to first observe that world in full detail and capture as many reference photos as possible. You'll be amazed what details your eyes didn’t actually “see” in person when reviewing the reference photos.
If you’re in a time crunch and need great reference material take a look at CG Textures. They have an extensive array of catalogued photos from leaking concrete to paint splatter and nearly everything in between.
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