5. Create a new layer (Layer > New Layer). Ctrl+Click the layer with the screw on it (This should make a selection around the screw) Now on the new layer, start ...
1. First, we're going to make a custom rusty pattern to use with the layer style. Make a new layer, set your foreground color to orange and background to black, then ...
This is very nice tutorial. I've also found one on creating nice grungy text here: http://tutmate.com/tutorials/photoshop/grunge-text-photoshop-tutorial