OP, no need to be afraid. As long as you use a light polish and a final polish or finishing pad on a good orbital you'll be fine! I was afraid too, but you really can't mess up too bad unless you use a harsh cutting compound and a cutting pad. Claying is very easy as well, and I guarantee you won't mess up, even with no experience
I would suggest you do your research on detailers (ask in the forums here for a good detailer in your area), a lot of places you drive by (especially where I live) offer a "full detailing" for your car. To them, that means running it through an automatic wash, rubbing it dry with nasty towels, vacuuming the inside, and giving it back to you. Don't take it to the dealership. They usually aren't the right people to detail your car.
You can look into the hard water systems for your hose, but IMO they are unnecessary as long as you are careful about drying your car in a timely manner. You don't have to pull your hair out and run around like crazy, just rinse it off and then dry from top to bottom with a clean and dry waffle weave towel. You can buy them on any of the detailing websites. The bigger the better, and they absorb a LOT of water. Get a couple of them, use one for each half of the car (that's what I do). It takes quite a bit, even with hard water, to etch into the paint. You'd have to let it sit and bake in the sun for a little while for it to cause damage.
FWIW, mine used to have the spots because I lived in an apartment and had to park it in front of my building, right where the sprinklers hit. They covered the car, then it baked in the sun. I could have moved it to the overflow lot and avoided the sprinklers, but a few cars had been hit and a few broken into back there, so I decided to take the sprinklers instead. That's how mine got the spots etched into the paint, but there wasn't much I could do.
I've never had any spots etched in while washing since the corrections I did, and I still wash it and dry it by myself
And before I corrected mine, I had no experience. I read a lot here and other sites on how to do it, then I just got out there and tried it. The results were better than I thought they'd be, and I was extremely happy I decided to do it myself!
Here is a link to my thread where I showed the damage I had, and after I corrected it. Note that this was the FIRST TIME I ever used polish or anything on my car. I was very happy