New player got a few questions

[Bixby]

You are right about your responsibilities as a tank. Get & keep aggro, stay alive, keep monsters in positions that aren't problems for the rest of the party (e.g., if a mob has an AOE move, make sure it's positioned so that won't hit the healer).

Flash every 20 seconds is either not often enough or too often, depending on the situation. You need to adapt to the situation at hand. If you've got enough enmity on everything to hold it off, Flash is basically a waste, since it doesn't do any damage. If you're about to lose enmity on something, sticking to a stringent timing of Flash just makes you lose it.

What I generally do is hit something with Shield Lob, then start Flashing once the enemies are gathered close enough. Usually Flash three or more times before I start using my enmity rotations. After that first bit of Flashing, the Fast Blade > Savage Blade ( > Rage of Halone once you get it) on the main target. Then start spreading that combo among all the targets (e.g. FB #1 > SB # 2 > FB #3 etc.). Throw in more Flashes as appropriate.

Through it all, keep an eye on enmity levels. On the party list, there are white meters under every party member that indicate his or her aggro on your current target. Switch targets around while you're waiting on the GCD so you can keep an eye on them and see which one will need attention next. (Note that if you're playing with a gamepad, you have to fully switch/select targets; subtargeting with the little circle doesn't bring up the subtarget's enmity in the party list.)

Also, read this. Every ability has an enmity modifier. The damage done x that modifier determines the enmity. Knowing which moves give the most enmity will help you know what order to spread your hits out in.

Also also, mark at least your first target as #1. DPS won't always follow that, but when they do, it makes things much, much easier. A few flashes should be enough to hold off healer aggro, and your single-target skills on one mob should be enough to hold off DPS. If the DPS aren't focusing on one mob, you can't either, and it just makes it that much harder to hold them.

[Alurwen]

You can get really good gear from your Grand Company as you level up, stick to things labeled as for GLD, PLD, MRD and WAR. The "Disciple of War" stuff is not as good for tanks and are for melee like pugilists and archers.

For keeping threat on multiple mobs, use Flash first off for as many mobs there are. Three mobs? Use Flash three times. Then cycle around the mobs putting combos on them while checking the threat meter on the party list, it will show you how much threat each player has based on the mob you have targeted. Things get MUCH easier when you get the 3rd part of your threat combo "Rage of Halone", forget what level that is, and then "Shield Oath" at level 40.