Retribution is your best bet for leveling. You want a slow two handed weapon to maximize your damage. And of course, you’re gonna be taking damage, so keep up on your armor. There’s a number of paladin leveling guides out there and they’ll all mention these things.
As for raiding, many raids tend to find Holy to be most optimal, but that is not saying that there isn’t room for non-healers. At higher levels, holy will give you quite a bit of performance, but you will want gear with spellpower to maximize that effectiveness.
Check out this build for Retribution: The Spelladin - new Retribution meta for Classic