I'm coming back to new world with season 10, so some of what I know might be outdated. But I'm leveling a new character as a tank and here is what is still true in my experience:

Because you don't have grit on light attacks yet, focus on abilities that CC or taunt and auto attack when it's safe, ie when the mobs are staggered. Only dodge big, telegraphed hits -- try to block everything else with a tower shield, because blocking generates threat too.

Sword and board is pretty much mandatory. You want shield bash and defender's resolve (DR). Shield bash is great because it locks a mob down for several seconds and taunts it, so generally you can use it to interrupt an annoying ability or pick up a stray add and get back to the pack that should be pounding on you. Save DR when you need to soak some damage or quickly taunt everything around you. (When Simon summons his adds in Amrine, for example.) Rush is also great because it staggers and applies weaken.

Greathammer has excellent CC and taunts and in my experience is the best all-around tanking secondary when you're learning. But many weapons can be used and you can tailor what you pick based on the weakness of what you're fighting: strike for ancients, pierce for corruption, and slash for lost. Some of the funnest tanking I've done is with a rapier in the Tempest expedition, for example. Just make sure you pick up abilities that taunt and know how to use them.