Increase my sales

This question comes up quite often and has been explained in detail several times here in the forum. just search, you can do it :)

These are just my personal opinions, but I think they can work for most people,
#1 way is to post lots of models and work your ass off. Try to make quality stuff as often as possible. #2 way is using social media and other community resources to show off your work. Make a Youtube channel, Artstation, and think of creative and artistic ways to present your models. It would also help if you know a thing or two about animating and rendering. #3 is to upload high quality renders and previews of your work for each model. Again, choose a quality render engine and really use it to your advantage in your preview images. Preview images help sell your model.

"Often" and "quality" are absolutely opposite things. Working too hard instead of increasing popularity and income you will get a nervous tic, sleep disorder, problems with the spine and tendons of the hand.

YouTube as a means of promoting 3D models is absolutely useless. If you do something really epic in Blender, 3DCoat or Mudbox maybe you get 250-500K views and hundred comments but even then it is so unlikely that you will have hundreds of new buyers.

As for Artstation it makes sense if you want to get a job in the studio and you have a really cool portfolio. If the goal is only to advertise your models should not count on a great effect either. The tactic of subscribing to half the world and liking and commenting everywhere also will not increase sales.

No need to chase quantity, first of all you need to understand what you are doing and what are weaknesses at work. It is better to spend a month working on sculpting the hand and forearm (for example) or studying the visceral bones of the skull than in a hurry to sculpt, not clear what, it is not clear how and why at all. It is useful to sometimes take a break and look at your work in 1-2 days. Attention to detail and regular skill development is what can increase sales. Social networks, YouTube, Vimeo etc. all this is secondary.

keep working