Well... my hands are almost always in my tank.
I am always harvesting algaes (the macro kind) because my tank is growing them like crazy. When I dont harvest, you cant see the fish because they hide in the macro algae.
Prior to putting my hands in my tank I remove all jewelry then, I always wash them really good with antibacterial soap and water, then rinse them very well in RO
water. I follow up with a similar wash when I am done.
I have been stabbed by my spinned sea urchin (OUCH!) and my shrimp love to climb all over my hands and pick at my dead skin cells.