Honestly, adoptables are a very overflooded market, more and more come out everyday. And people tend to make them in large batches.
Honestly, maybe a good piece of advice I can give you (and I dont know what will help but this what I have noticed as a buyer.) People are more interested in adoptables if they have detailed refs (front view, back view, headshot etc.)
If they are off base (I.E they dont use "bases") I dont know how often you are making adoptables but maybe try a quality over quantity approach? Make your own base maybe, attach a mood bored and make maybe 1-3 adopts that are super detailed.
Versus coloring in base with 10-15 adoptables and hope it sells. Adoptables that are more detailed tend to sell better especially if you don't already have a following.
TBH the only time I see base adopts sell is if that artist already has a following and people are already clamoring for their designs. I'm not saying other people CAN'T sell adopts... its just I've noticed a trend between selling and already having a previously established following.
Id say 100% quality over quantity. My best advice would also be look into what adoptables are popular. What art/adoptables are popular tend to change. Just like fashion.