I have experience with Neutrogena spray from the drug store that you rub on yourself at home (about $10?) -- which frankly is somewhat better than my 3 experiences with spray tans at Planet Tan. They also sell some from department stores that are "supposed" to be better. Follow recommendations on label.
The medium level on the newest machine at Planet Tan didn't do well for me last week. Last year, I did it on the older "Versa" machine and I think it was better and its Medium wasn't as dark and uneven. Follow their recommendations but they will try to convince you to get 3-5 products right now because they are 25% off now, not later.
If it is too dark in some places, use soap and water and washcloth and scrub just a bit when you see it. Not the next day.
The same place sells a spray tan in a can for home use to "help even out" that tans immediately. I don't know if it lasts through a shower or not but it did have a great color and was pretty easy to apply evenly because you can see it immediately. It costs about $42 without a membership discount I believe.