Ryan, I know how you feel. I got my WSM about 4 months ago and was a bit nervous doing my first smoke (Costco BB's). I've done a dozen or so smokes since then and here are some things I learned:
1. Have your meat at or near room temperature
2. Don't put the meat on the rack until the WSM is at the desired temperature.
3. Water or not is up to you. Frankly, I'd ditch the water. Line the water bowl in foil and place a foil-wrapper terra-cotta planter base in it.
4. Don't sauce the ribs at the start. A light coating of a good rub is all you need. There is time for sauce later (if needed)
5. Don't try and control the exact temperature. It will vary by 10+ degrees up or down as the smoke progresses.
6. Remember the WSM mantra..... "LOW and SLOW"... and... "It's done when it's done".
7. While some here may disagree, I re-use the unlit coals. When you take the meat off the racks, replace the lid and close all vents. The WSM will cool off after a couple hours. Shake out the ash and small bits and leave the unused coals for the next smoke.
Let us know how it goes.
7. If you want "fall off the bone" ribs, foil them at the 3 hour mark with some apple juice (I prefer a mixture of apple cider vinegar and brown sugar)and put them back on the WSM for 1.5-2 hours. After which, open the foil, brush with your favorite sauce (Sweet Baby Rays) and let cook for another 30-45 minutes.