Hi there-
Firstly, how much time will you have? Since you've not done it before, the sooner you can do a total tank disinfecting, the better. But takes several hours (much of it waiting for things to finish bleaching), so if you don't have this much time, I'd recomend this:
Fill two clean spray bottles with vinegar and hydrogen peroxide.
Unplug your UTH (yes, if cold water is applied to the glass above it, it can crack the glass) and lightly mist vinager onto the walls and floor. Let that sit for about 30 seconds, and then mist the peroxide on it. Let that sit for 5 minutes, then wipe dry. Hydrogen peroxide breaks down to water and oxygen after about 30 seconds but paired with the vinegar it can efficiently disinfect smooth surfaces. I usually spray both on, wipe the excess off, then re-mist with the peroxide (then wait another 30 seconds) and wipe totally dry, just to get all of the vinegar residue off.
If you're using paper towels, replace with fresh.
Spray the peroxide onto any tank furniture/dishes and let sit in the sink for 30 seconds before thoroughly rinsing. You can then (carefully) microwave any WOOD pieces after they've drip dried a bit, or place them outdoors in the sunlight.
Rinse out the humid hide, and if you're using paper towels in it, replace that.
Also, please visit http://www.anapsid.org/maincleaning.html . It has some excellent information relating to herp health and sanitation.
Hopefully some other members will be able to offer some more insite 