How exacly does 'Top 3D Models' selection works?

I don't think that Top 3D models selection algorithm cares much about preview images or description. Much more important are model views and likes count, sales count, model rating and even seller's reputation score. It's quite hard to reach top list untill you gain some reputation on the site. Work tirelessly towards your goal, constantly upload high quality assets, try to attract more viewers to your models and in no time you'll notice that many of your models will hit tops without much effort ;]

I've managed to get that spot a few times and it happens when you are able to get lots of views in very short time. So what you need to do is upload the model set presentation in place and then quickly harness all your external channels to boost the traffic in short time (use things like your Facebook page, Pinterest, Artstation, polycount, basically everything you have).

If you manage to get average of 60 views in few hours then that usually is enough to get you there (depends on how large the average gets that day).

You can enjoy some more visits to your profile and get few more likes/followers during that time on display of the front page but it does noting on sales (at least not with me).

My sales is relatively good regardless of getting up front as I rank well in Google with most of my stuff so I would argue that getting your Google rank great is more important.

Managing to get traffic to your stuff helps in this regard so use everything you can get to trow at your pages.