Mini-games
For gameplay assistance I would actually advise against it, you'll enjoy the game more if you don't tunnel vision your abilities, performance whatever.
Try to play with friends and challenge yourself to open your eye to the big picture ie look at what the enemies are doing as well as your own team, try to find ways to help.
Playing a swiss-army knife type of character has much more longevity than single-minded-ly fulfilling your "role" in the narrowest way possible.
Although "good dps numbers" might shield you from some of the most unsavory elements of the wow playerbase in the long term your enjoyment will suffer for it.
That said if you do want to try a rotation helper I think
Bitten's SpellFlash: Paladin (you need all 3 components) takes the best approach by re-using a familiar mechanic from Blizzard: ActionButton Flashing.
Finally with regards to making your UI better looking overall I think for new players the best approach is to try a full-UI package, or UI compilation as they're called.
Popular / well tested options include:
Or browse the
Compilations & Suites category yourself.
You'll get a good idea of what different things are possible and eventually might go the "advanced" route of
building your own interface from scratch which is optimal as you're the only one that knows what suits you best.
I don't however advise starting there as you can quite easily get lost / frustrated with the myriad of different addons available for each part of the interface.