1. Read my guide (linked in the signature). The following bullet points (and why I mention them) are all in there.
2. Get a second profession up (mining is easy and quick)
3. Therazane reputation for shoulder enchant
4. Cloak enchant 250 armor and Chest enchant 55 stamina or 75 stamina. Also leg enchant is missing.
5. Talents: Wrath of the Lightbringer is the best threat talent you can get. Move the points from Eternal Glory to there. Hallowed Ground is a pretty useless talent, move the points in it to Reckoning and Seals of the Pure.
6. Glyphs: Seal of Truth (Prime), Shield of the Righteous and Crusader Strike/Hammer of the righteous are the only real choices for Prime Glyphs. Focussed Shield (major) for single target fights, dump the Consecration major, it is worth about 400 damage every 30 seconds. Situational usage: Lay on Hands, Holy Wrath, Divine Protection.
7. Gems: Puissant Emeralds (Stam/mast) in blue, fractured amber (40 mast) or puissant emeralds in yellow, defender's demonseye (parry/stam) in red. Fractured chimera's eye (67 mastery) in the belt prismatic, relic prismatic and one other yellow socket.
Thank you for the advice. I fixed my talents right before reading your response, and i'm currently working on therazane rep (halfway to exalted). I do have other professions, just on different characters. Even if my alt is mining capped, should i still lvl mining on this guy just for the stam buff? And also, which seal do paladin tanks usually use. I used to use seal of insight mostly for the healing but i see most prot pallies use seal of truth for extra damage and threat. I can hold aggro just fine, wouldn't the extra heals from insight be better?
As to the professions, it's really up to you. Having a gathering profession can be a good way to kill time when needed. Waiting for a guildy to be ready to queue up for a random? Just grab some ore while you wait. The downside to gathering is that the benefits are weaker. The stam bonus is better than a poke in the eye, but not really worth much in the overall picture. Min-max for almost any class and spec is blacksmithing and jewelcrafting. Combining extra sockets with the extra large gem cuts generally nets the biggest gain, but by a VERY small margin. Also, that combination allows you to use whatever gem is best. So for dual spec, you get just as much benefit out of both professions. Stam does next to nothing for a healing spec or dps spec as your off-spec.
The big key is just to have SOMETHING. Get two professions leveled for the bonus. It's free...just takes some of your time. If you want to use an alt to provide the mats for two crafting professions, awesome. Rather have a gathering profession on every toon for more opportunites for gold? Awesome. Just get them high enough to get the bonus at least.
As to the seal...seal of insight is nice if the healer is obviously struggling or dies. Othewise, you will be better off killing the mobs faster. That will let the healer keep up better than the heals you get through Insight. Most healers can handle most burst (assuming you are using cds correctly, not standing in fire, etc). The question more often is longevity. Can they do it without going out of mana. Killing faster is more effective than 200 healing per second from insight.
Seal of Insight heals for about 4k every 5ish seconds. That is about the same amount as a hoT that crits a little more often than normal. Healers won't rethink their healing strategy if you heal yourself for 6k (this is about 2-4% of a tank's maximum health, a greater heal produces 35-40k healing if it doesn't crit). The healing from SoI just gets lost in the "noise", only use it to get your mana up after being combat ressed.