Male_M3dia is spot on, it's often more about creating a brand for yourself, that will draw custom due to a reputation of creativity and quality. At times it can also be about finding a niche or segment that hasn't been overly exploited in the market already or excelling in an area that is already well established. The problem when entering well established market areas is that you will need to give buyers a reason to buy your product above, or together with, other vendors/PA's that they already know and trust. This is where building a good reputation is crucial.

My best selling products in the past have been those that were just a bit different than what was available at the time, or delivered more in as far as quality or value for money than existing products. Market research is always helpful but the proof is always in the eating or selling in this case. What's Hot or Best Selling can tell you a lot about the existing customer base and what they are currently buying, but just as importantly it can show you what they are not buying in each marketplace.

Also try not to make this a drudgery for yourself, make a it a labour of love and you will enjoy it more and will be much more creative and unique into the future. If you love creating spaceships, do that and test the market for your own style of spaceship, don't just change your own style or direction after advice from a 3rd party telling you that what the market really needs is more 'real world clothing for males' and then expect whatever you make to sell a million based on this advice. Often those that scream the loudest for a particular kind of content, are asking you to deliver on a niche that most content creators avoid, knowing the market in this area can be fairly small and will rarely see a decent return.

Product complexity is always something to keep in mind in this market. An extremely complex discombobulator thingamajig that took you six months to model, UV, texture and prepare for sale is going to be a tough sell (for a decent return) unless the demand for that particular item is huge. A concept you should look into is ROI, Return on Investment. This concepts is built around the idea of balancing the effort and time spent on creating a product vs the expected return when the product is made available to the market. This means that is not a good idea to spend 6 months on a product that is likely to sell 100 copies at $8.95 retail, well you can if you don't intend on making more than $1000 a year from this and you just want a hobby to pass the time with. Which is also fine if that is what you want.

Another concept that has helped me in the past is scheduling, try to pick a number of products to create over a specific time period and attempt to stick to it as closely as possible. If you are able to do this, it is possible to roughly predict a path to a viable income stream. The same as any business needs a business plan to know as to on how many items they need to sell each month at a specific price, to keep the doors open into the future.

One other thing I have found valuable is collecting images in a folder that inspire and also making a list of potential product ideas and ranking them in order of expected interest from both myself and the market. Of course it becomes easier to rank a product for expected market interest after you have made a few sales, but a general idea at this point is all you are really need. It can also help to factor in ROI, an Intergalactic Planet sized space ship may have good market appeal, but is it feasible to create in a realistic time period and see a decent return on? Maybe a much simpler Ship Airlock may be a better idea for a product based on ROI and expected market interest. But if you do want to create an inter-dimensional planet smasher, than by all means have at it. Just make sure you go into it with eyes open and with some kind of plan as to what to expect from the project. Two planet smasher a year may not be enough to keep a roof over your head if you intend on doing this as your primary income.

Hope this helps,

This page has some useful info also: https://www.renderosity.com/product-submission-guidelines-cms-13759