Just a small addition to the first step:
I would look for a niche that stands away from the crowd while looking at sponsors and alexa etc. Out of those 5000 submitters probably 70% of them are doing all reality and Teen submits with moms and lesbo running a tight second.
You brought up an interesting stat that would be greatly affected by making a niche choice - the fact that the sale ratios on the galleries are so lackluster is explained pretty easily by the niche. While a sponsor can be underpromoted the niche can be way overpromoted and also affects your listing chances at many TGPs. Ive submitted some niches in the past that are almost always guaranteed to be listed and make fantastic sales, while others I see posting here wondering why they get 1:20k ratios and only listed 50% of the time.
Just something to think about
