Don’t press Enter at the end of a line!
Word processors will break words across lines automatically, and if you find yourself having to force-break to get the layout you want, you should probably be using custom margins, multiple columns or tables.
Don’t use extra spaces and tabs to line up text!
Spaces vary in width between printers and fonts, so text that uses spaces for alignment will actaully NOT be aligned when printed. If you use justified paragraph alignment (such that both left and right paragraph margins are “neat”, like in a newspaper) then the word processor will “stretch” the width of spaces to fit.