It's impossible to be too well armed. Remember Colin Powell's theory about entering a conflict zone with “overwhelming force”. Make sure you have lots of examples of your good work – targets met, contracts renewed and expanded, positive references from clients, colleagues or supervisors. Where possible, bring any written references with you, and leave them with your boss so you won't slip straight out of mind when the meeting's over.
Above all, do everything you can to make it clear that you are a valuable, high-performing professional. As your boss should know, people like that are hard to find and can very quickly get snapped up by a competitor.
