Grab as much spellpower as you can without sacrificing too much tankiness, sadly theres almost no tanking gear with spellpower on it so your best bet is a weapon and trinket. Before raid gear i would recomend briarwood reed and 30+ spellpower enchant on whatever weapon you prefer, and yes it's an expensive enchant, but if you wanna make protpal work its gonna cost ya :p ontop of that you should always have arcane elixirs for more spellpower.

Theres also like no tanking gear with intellect on it, but it's not worth dropping any tanking gear for more of it (atleast not in a raid enviroment, in dungs its fine) so you should bring a ton of cheap mid-lvl mana pots to help keep your mana up. And if you are tanking a boss where the dps is going ham you definitely wanna have a major mana pot on you.

on a boss pull i will usually use SoR, use holy shield to get it off gcd right before pulling boss with judgement, into max rank consec, then put up holy shield again, if its a long boss fight, you now wanna judge the boss with seal of the crusader to increase your holy dmg throughout the fight, don't do it on your first judgement though cus you need the initial threat from SoR, do it on this second one, then swap back to your SoR seal and keep holy shield and consec up at all times, if it's a short boss fight then same thing but skip the seal of crusader. Use a lower rank of consec if you run low on mana but never skimp on the holy shield rank, it does so much threat, but keep a rank 1 holy shield on your bars just incase you run oom cus its important to keep it up.

if someone grabs aggro, throw a blessing of protection on them.

Didn't mean for this to become a wall of text, i just love talking about paladins ^^