Mitigation is important, not just raw health. I wish I could tell you that I remember what my Guardian's mitigation was around fresh 50, but I do not. I would try and focus on shield/absorb with overall defense as a tertiary priority unless it's lagging too far behind. It may seem counter-intuitive given the nature of certain Jugg procs on defense, but you'll get your most bang for the buck with shield rating and absorb. If you can augment gear for it, do so.
Grabbing some good crafted epics heavy on shield, absorb, and defense would be worth investing in. Also, pick up some fortitude stims to give you an extra boost. Prototype hyper-battle stims will also boost your defense as well. Try and use your cooldowns as effectively as possible. Juggs have arguably the best defensive cooldowns of any tank in the game. Above all, don't be afraid to get out there and try the content.
I'm a relatively fresh 50 with a few extra little things I got from the Black Talon:
Health: 15360 (around 16k with buff)
Damage reduction: 44.31%
Defense chance: 18.83%
Shield chance: 35.68%
Shield absorption: 27.65%
Critical chance: 12.38%
Critical multiplier: 50%
Also use a relic that will boost my shield rating and absorb by 185 and another that Alacrity by 355.