Hey - I'm no pro earthguard but here's a few tips.
Armor
Use leather. It gives you the best of both worlds and you can have int on it. Having armor with int is really important. For an offhand a regular shield is fine but there's a leather offhand you can find too. Later I switched to a book to get light armor up as well but that's personal preference. I'm going to test light down the road but I think you need to be really gear carried for it to work.
Stay REALLY up to date on your armor too. The minute you can upgrade tiers, do so. It helps you stay at the current mob lvls well and gear check lower lvl mobs quicker.
Skill Rotations
For early game your options are limited but your bread and butter is getting Earthstruck applied to mobs and Earthshield applied to yourself.
You HAVE to keep damage reduction buffs up. Really focus on having either Earthly absorption buff going and refreshing it with protective shards. If you lose your DR buffs you're going to die.
I'd push to lvl 10 elementalism then try the following:
10: pull with protective shards, stack, pre-pop aftershock, once 5 stacks is on a mob use earthly absorption for 5 stacks of earth armor, refresh stack with protective shards at ~7 seconds left on earthly's cd
15: pull with protective shards, stack, pre-pop aftershock, once 5 stacks is on a mob use earthly absorption for 5 stacks of earth armor, refresh stack with protective shards at ~7 seconds left on earthly's cd, weave Siesmic when off CD or when you need a breather
20: pull with protective shards, pre-pop aftershock and geometric spikes, group mobs and use solid core, immediately use earthly absorbtion + seismic slam, old lvl 15 rotation