Anyone earning with Merch By Amazon?

I got accepted almost 2 months ago now and only have 4 sales with 23 of 25 designs up.

I am a designer and sell shirts on Spreadshirt without issue but mostly get traffic from social media. I however sell in a very small/targeted niche so it's not hard to rank.

With Amazon I wanted to try selling shirts with funny cartoons and jokes, which is very different from what I have sold in the past. But Amazon has a more "mainstream" audience so I wanted to try comedy that appeals to a more "mainstream" crowd. My designs for this new brand get plenty of engagement/likes on social media but I am still not seeing sales.

I can't find much solid info formatting descriptions so I wanted to know how you guys were doing it.

If I wanted to add a list of long-tail keywords would I put it in the bullets points or in the description at the bottom?
Is there any limit to how many keywords I can use?

What is your experience with Spreadshirt?

Funny cartoons and jokes sell and not only on Amazon. I don't think Amazon has a very mainstream audience, considering there are millions of visitors a day there are bound to be all sorts of people. I've tried social media as well but no luck, organic sales seems to work best, which is great since I don't have to do any marketing work and I can focus on designing

As to the formatting - just don't overdo it by stuffing too many keywords, it's going to look unnatural and ugly. Everyone seems to be reporting different things - stuffing, not stuffing, long-tail kws, full sentences, just words, empty description, and everyone has different results. I don't think anyone knows what exactly is best. Just go the old trial and error way - I check what works for me and then I do more of the same.