DO use a document setup size (i.e. your page dimensions) that is the same as your trim size. For instance, if you are creating a 6 by 9-inch book, set up your initial page size in the document setup for 6 by 9-inches
DON'T create 6 by 9-inch text frames in a 81/2 by 11-inch document setup and manually add registration marks.
DO make page elements that bleed extend at least 8th of an inch beyond the page boundary.
DON'T use your page layout/desktop publishing program's predetermined “hairline” rule. The width varies from program to program, and prints out differently on a laser printer than on an imagesetter, if it prints at all. Don't create rules that are less than .25 pt.
DO watch for widows, orphans, rivers, bad kerning and other desktop publishing no-nos that will make you look like an amateur. Get rid of double-spaces after periods, don't use spaces to align columns (use tabs) or to create paragraph indents. Know your en dash (–) from your em dash (—).