I don't think tanking is so much an art as it is an experience. A good tank is defined by their gear/spells, their pull speed, and their knowledge of positioning.
There are plenty of threads on the boards about gear and spell order for SK so I'm not going to waste time on them (or the importance of timing your autoattack)
As for the other two, there's no easy way to "teach" that stuff because it is unique to every zone, and you just have to learn it by doing. (or watching a tank do it)
To give you an example in Deep Forge right before the first named there is a mob you can range attack that will pull half the room without bringing them named (which is good). But if you don't know that via experience, you either have to pull one group at a time (which slows down zone progress) or you bring everything, which will wipe most pickup groups.
But that's just a piece of advice how to pull a single part of a single zone. And theres something like what -- 25 T8 instances out there, not including raid zones.
As far as general advice goes for an SK, you're not too far off the mark. However SKs don't really have temp buffs like warriors do. They're all a waste of casting time except the single target ward, which I will pause to refresh between most pulls if it is used up.
Try to use dots early in the fight so you can get more efficiency out of them; there's little point in hitting the mob with a 24second dot when its going to die in 2 seconds.
Don't bother with your taunts unless you are in a group where aggro control is a struggle. Instance mobs die too fast for the debuff on the AE taunt to matter, and the efficiency of the damage on the single-target taunts are ok but not great. You're usually better off critting a damage-dealing ability than landing a taunt that cannot crit (well technically the damage portion of the the single target taunts can crit, but not the taunt amounts)
One situation where you DO want to make sure you use taunts is whenever you body pull mobs that have large social radii. In those situations you want to make sure you have just enough threat to keep the mobs from plowing into the healer on the pull, and taunts are the quickest way to do that. (Autoattack is slightly faster, but it has a higher miss rate)
Range pull whenever you can, but know ahead of time how many adds you're going to bring. SKs have some of the best unlocked-AE aggro in the game and its foolish to waste it body pulling everything, but its also foolish to pull more than your group can handle. Thankfully, having FD makes it much easier to experiment with range pulling compared to other tanks.
Always turn mobs. It makes it easier to tell when you're losing aggro. It also lets you focus more on your hotkeys and spell order, so you don't have to watch the new aggro thingy to find out if you're losing aggro. It also makes things easier for scouts, but that's not the important bit to me
Learn to use the mouse wheel to keep an eye out on wanderers and plan out your next pull, all while fighting the current mob. If you don't have a wheel on your mouse, consider getting one because it does make a difference when you're chain-pulling
Conserve Death March for named and AE encounters. It is good on named encounters as a type of temporary buff (the casting haste can be useful to your healing unloading all their specials on the pull) and its good on AE encounters because it can last longer than 10 seconds. However if you know there is a stream of singles ahead of you, use it whenever you can and don't bother about the timing.
Dont forget that your FD can be used on group members; ocassionally it can be helpful to FD a squish on memwiping mobs. However I would not advise using it on people who are pulling aggro on normal encounters, as it is more annoying than it is helpful.
Don't feel bad if you see dps people pull aggro and die. On my warlock when I pull aggro it is usually by choice. I do it in order to clear the zone faster, and I only do it when I think I have a good chance at surviving. If I result in dying, the fault is more on my own judgement of my survivability than it is on the tanks lack of aggro control. There's not a lot a tank can do to bridge the aggro gap between casuals and raiders except to stack the group with lots of hate buffs/debuffs.
DO feel bad if either yourself or your healers die, because whenever that happens its usually your fault. (the usual reasons being bad positioning, lack of gear, or being lazy with your abilities on the pull)
Most of your money should be invested into buying masters. Look at your parses in ACT to see which abilities are doing the most damage, and compare that to the prices on the broker so you can get the best bang for your buck.