Finally, consumables are very helpful. For example, once you're on Timeless Isle, you should head to the Cavern of Lost Spirits, just north of the Celestial Court. The spirits there are usually farmed for their pet drop, but if they aren't, clicking on the bonfires gives you a fire resistance buff that makes them a lot easier. Your goal here, though, are the Eerie Crystals scattered on the ground. They can have a Crystal of Insanity inside of them. An extra 500 strength and 500 stamina will help you kill faster and survive longer for sure. Also, be sure to take advantage of any buff items that drop off mobs. There's a healing proc drop, a stat boost proc drop, and a damage proc drop. Once you've been on the island for a while, you'll probably find you have a stack of each in your inventory and can keep them up all the time -- as long as you aren't dying too much.
Once you're properly outfitted, the time has come to fight a few elites. When fighting an elite, you want to make sure you have your basic rotation down pat, but especially, you want to remember your defenses. If you are facing an enemy that does a lot of unavoidable physical damage, remember Icebound Fortitude. Death Adders are an excellent for for this. You can't really actively dodge Huge Fang, but Icebound Fortitude can take the edge off. Of course, if you're soloing as a tank, you'll have all those extra blood defenses too, such as Dancing Rune Weapon.
For magical enemies, consider your interrupts and Anti-Magic Shell. Anti-Magic Shell is not only a great way to not only absorb a massively harmful magic attack that might otherwise kill you, but a great way to boost your DPS with the extra runic power it provides. Interrupts are a little trickier, if only because many abilities won't work for them. Essentially, if your enemy is casting a basic bolt spell of some sort, or if they are casting a player spell like Pyroblast, you can probably interrupt it. Everything else likely won't be interrupted by anything less than a stun (or in some cases, a Death Grip, if you can get out to range and cast it fast enough)
But what happens if you can't interrupt, and your other defensive cooldowns are on, well, cooldown? This is where you're in luck. Timeless Isle sets up most major attacks so that they can be avoided in the same way you'd avoid "the fire" during a raid. Is it a frontal cone attack? run through your enemy. Point blank AOE? Generally you should have time to run out of range if you start just as it casts. Not sure what type it is? Look at any magic forming on the ground and get out of it.
That brings us to the next trick. If you can, consider picking new glyphs and talents to help you survive Timeless Isle. Glyph of Regenerative Magic, Glyph of Dark Succor, and Glyph of Anti-Magic Shell are all excellent survival Glyphs. Use all 3 when grinding and you may find you can absorb most magical elite attacks (aside from the higher level yaungol and dragons) and chain pull mobs with Death Strike heals.
On the talent side, you can use Death's Advance to run out of major attacks faster, or Asphyxiate to stun an elite and get some breathing room. Be sure to use your healing talents. I prefer Death Pact for a big hit right when I need it, though Death Siphon may work if you feel you'll need healing a bit more often. You can also use it in conjunction with Purgatory, though I prefer using Lichborne or Anti-Magic Zone for that tier. Finally, I'd recommend using Remorseless Winter as your final talent. If you're fighting a particularly difficult enemy, or get unexpectedly swarmed by multiple enemies, Remorseless Winter can buy you enough time to heal or escape.
One more silly little tip I'd pass along is to learn the value of Path of Frost. I've actually escaped from huge packs of tigers when running across the island more than once by Path-of-Frosting across the middle pond. Whether you're in danger for your life, or just really want to turn in your daily without fighting 10 more mobs, it's a nice trick. There's also a specific rare, Evermaw, that swims around the island. With Path of Frost, you can reach him and help others reach him easier, and get that easy rare loot.Stay equipped, stay focused, and you too can conquer Timeless Isle.
Learn the ropes of endgame play with WoW Insider's DK 101 guide. Make yourself invaluable to your raid group with Mind Freeze and other interrupts, gear up with pre-heroic DPS gear or pre-heroic tank gear, and plot your path to tier 11/valor point DPS gear.