I just took delivery of a new car a few months ago. Here is my advice.
After reading the forums I chose products, kept it simple and committed. There are so many choices out there it is difficult to make a choice. Don't get sucked into trying this or that or the latest thing that is touted here. You'll be loading yourself up with unnecessary self-doubt and remorse. Just pick something and go for it. You cannot go wrong with any of the house brands here, but there are plenty others that are also competent and will work just fine. If you try to over-analyze and over-optimize you'll just be in a vicious circle of loading up your garage with surplus products.
The only decontamination I did was a thorough clay bar but that yielded very little, the finish was slick already but it was more for peace of mind. I did not use any iron-x or other iron product.
For sealant I chose Wolfgang Deep Gloss Paint Sealant 3.0. Why? Because among the multitude of suggestions I read here this one seemed to get the most positive responses. It was a matter of 5-10 different approaches and I had to choose one so this one was chosen. "Easy application" was the main attraction.
To top DGPS I chose Fuzion. Why? Because I just paid $40K+ for my new car (it is a weekend driver and sits in the garage during the week) and it seemed like the appropriate match and kept it in the Wolfgang family. This is probably not an optimal decision criterion but it makes me feel comfortable. Fuzion goes on like a dream and wipes off like a dream, too. If I did not use Fuzion I was going to top it with Collinite 476s paste. I am a big fan of paste waxes applied by machine.
For wheels, tires, trim, windows and headlights I used other products which I won't name here since they are all pretty good. I have too many products now but three other vehicles to use them on. The new car gets only DGPS and Fuzion. The other three vehicles get whatever appeals to me at the time of application.