Use a negative that has a good contrast range, like everyone already said. A more "contrasty" negative will work better than a flat one. For mine, instead of using a dedicated splitback printing frame, I used a regular wood frame that you can get at any Thriftee's or KMart. Since this is a printing out process, all you have to do is expose to sunlight or ultraviolet light and then rinse under water in a tray, or under a faucet.