The key when breading fish or meat is to use one hand for the wet ingredients and one hand for the dry. First, dip a fillet in the egg white mixture with your wet hand, and place the fillet in the breading mixture. Then, with your dry hand, dredge the fillet in the beading mixture. This technique prevents your hands from becoming covered in the breading.
Try this Kitchen Shortcut with Crisp-Crusted Catfish.