The steps for photo-etching are nearly identical to the process off creating etched circuit boards.
1.) Mask areas that need to be left behind.
2.) Insert into acid bath.
3.) Wait appropriate time, too short not enough metal has disappeared, too long and too much has disappeared.
4.) Take out wash, rinse and use.
The imrortant steps are good masking, layout design and etching time.
Note: It takes quiet a bit of testing and experimenting to get the feel for the right timing, etc.