The issue with tanking ( just started back up myself ) is PUG's. The first thing I do is look at a healers gear. That gives me a good idea of what I can and can't pull. Secondly I usually ask if they are ok with bigger pulls. I personally dont trust PuG healers. Often they are either over healing or DPSing and zone out and let me or other tanks get way to low. Healers need to know their class and I feel like a lot of healers only made healers so they could get fast queues lol.