The spec

There are quite a few small variations on a proper ret spec, all to do with the player's individual gear, their main venue (PvP vs. PvE) and the functionality they're looking for.

So what are you looking for?

If you want to be able to heal decently, a 20/0/41 build with 5 points in Illumination gives you very strong longevity and allows you to take advantage of all the healing gear with spell crit for Pallies.

Tanking is pretty limited with a ret spec but 5-mans and maybe even the occasional OT in a raid (if NO ONE else is available) is do-able as long as you spec for Improved Righteous Fury and Kings (that's a 0/14/47 or 0/20/41 build).

A little bit of balance between all three trees isn't a bad idea (healing without Divine Focus will make you cry), which is the basis for my current spec (9/11/41). Nailing that spec gives you enough Focus to get away with healing out of the bubble (put up conc aura if you can afford the GCD), the precision talent which is GODLY for Ret DPS (see future posts) and Kings to make your raid happy.

I'll link the builds recommended based on these points in a later edit. Your focus should be upping your damage as much as possible, while still placing points in basic skills that will help you in other tasks you like (aka, healing).