The most important thing is really shared by all classes and specs. Always be doing something. Never be idle even for a few seconds. It's like this poet said, "how dull it is to pause." Other than that, a few things to keep an eye for. I'm assuming you're already comfortable with all the Hand spells, using them on yourself and on the raid, all at a time when full benefit can be gained from them. Cuz that defines any good Paladin, not just Prot ones.
EF is not just to heal yourself. Strong vengeanced-out EFs are pretty good on raid members/other tank, so are strong Light's Hammers. You're practically a 3rd raid healer on Malkorok (if you're two healing), and other boss fights. Many Prot Paladins capably solo heal both Spoils rooms with early healer deaths. Also ending Malkorok with 150k+ HPS feels pretty good
Active mitigation. While many say it's a no brainer mechanic and you can just spam it as HP builds up, clever use of it makes for a better Prot Paladin. Use it freely but never put yourself in the position where you'd be HP starved right when you need it active. On Garrosh, for example, i've seen numerous tank deaths happen right after the off-tank taunts. For progressing guilds/low gear, you should taunt and simultaneously Shield of the Righteous.
Can't think of anything else other than change glyphs depending on the fight. Stuns on Holy Wrath, single target Avenger's Shield, Hand of Sac, etc...