I don't PvP that often (especially not with my Hunter), but I still found this list of Hunter macros over at Huntman's Lodge really awesome. Whether you just want to make some common tasks easier (the one-button target/Hunter's Mark/pet attack/start attack is a macro every single Hunter should have), or you want to cut out some keystrokes (the /use [target=player] Heavy Frostweave Bandage is a macro that's great for every class out there), macros can provide a lot of solid support to your game in any situation. For some reason, we all use addons, but macros are generally overlooked, despite the fact that the system Blizzard has built in for macros can be pretty powerful all by itself.
Garwulf has even more macros for Hunters on a special page, and of course there are lots and lots of suggested macros and macro guides available online. Especially since macros started being saved to the server instead of your individual machine at home, if you're still using regular abilities on your bars, looking over the available macros for your class should help you out a lot.