Products that born, live and die?

It is both right and wrong. It depends on your product type. If you are selling electronics i.e. cell phones they will be less visible and sales will drop down in most two months. For cars this time is about two years. But for other models such as landmarks there will be always chance to sell later years. But this will be less amount of course. So you should clarify your needs. If you are going to work for stock marketing for long time and need money focus on best selling items. But if you are working at another job you can consider working on projects you want.
I hope this answer is useful to you.
Good luck

Don't fully agree, this website has very good search features that are easy to use, in fact you can filter on trending, newest, oldest, price range, file formats, animated, rigged and low poly.

Having your product on the frontage does not necessarily mean it will sell.

(Swan3DStudio, the point you make may not have correlation to visibility, but maybe more with the demand for a given item) Electronics like cell phones are coming out every month and then need mass marketing. Cars get a new version ones a year so new 3D models also need to be made then.

Having some very nice representative models/renders on the frontage that convince a buyer he may find what he is looking for on this website is more important. (more likely he will spent time to use the search features)

It is important to represent your product as good as you can, also make sure it is tagged well and have good descriptions, it all makes a difference whether or not that buyer is convinced your model is the best sale.

You should also focus on the strong points that make this website stand out of the crowd. No barrier between seller and buyer, adoption to al social media (e.g. Youtube,Vimeo, Facebook, Twitter, Pinterest, etc.)

Next you get good marketing tools like coupon generator and build in communication support. The website also looks very professional (nice layouts, colors, tools, information presentation, nice profile page, etc.)

Apart from all this, the remarkable service that is provide here is supper cheap. Hosting you models here is completely free, small fees are paid when a model gets sold and needs to be reactivated (this works automatically when enough credits are on your account). Ps. This has no influence on you model ranking.

So all the tools are here, you just have to use them well and make good decisions.

Nice, thank you for the feedback. Looks like it is not as bad as I thought. But as I am very new here I would appreciate a lot if you help me learn a little more.
Firstly, how can I know if my product is well tagged or not? Probably depends on my product, but is there any tips that you may want to explain to me?
Secondly, how can I generate coupons?
And finally I would you to take a look of my first upload and see if the description, price, taggs and renders are good for it? You would be helping me very very much.

https://www.cgtrader.com/3d-models/plant-tree/leaf-tree/lowpoly-leaves-pack

Thanks for the attention (;

About the tagging;
(in a nutshell ) Your model is well tagged if you are able to ad keywords that closely match the content your providing and the search phrases a searcher is going to use when he is searching for it.

It's hard to predict what kind of phrases a searcher is going to use. Many times the one who is performing the search does not know the best phrase, so he try's different phrases to see what kind of results he gets. So it's important (from the provider perspective) to make a sort of tag cloud that can match the different kinds of phrases the searcher may use.

In this case you did very well,
See only some small details, one for example may use the phrase "low poly leaf models" you would have three hits on this phrase. So maybe ad also "models" (the plural) and you would have four hits. One also may search for a "given" leaf (oak leaf for example), so you may want to add the tree species where the leafs are from. Some people may want a general view of what is available and use a phrase like "game vegetation" or something, so vegetation would also be a good tag.

About the coupons;
Generating coupons is very easy, just hit the big "My Sales" button and then go to the last tab "coupons". It's al very self explanatory when your there, just hit the button create coupon, select the products and expiration date, % of discount and so forth, a code will be generated to use as coupon. You can mail it to clients ore use it on social media (be creative).

About your product presentation;
Seems very good to me, maybe some small details, how large are your textures?
Tip: try to get into the skin of a buyer, what would he like to see and know?
(sometimes the buyer does not exactly know, so try to surprise him with good and exact information) I am also learning this sort of things along the way and there is no exact science to it. Its a human dialog from buyer to seller, so you would want to make a good personal impression and make a bond based on trust.

Nice iterateCGI! Everything you told me is going to be really helpful. About the price, what do you think, would you pay for it if you needed or even just because you found it useful?

Jess price is very good, I would even set it a bit higher.

Seems you got everything in place to make it a best seller. Unfortunately the work does not stop here, you need way more products. The one attracts the other so you need more ones and others.

For example, you would have some Speedtree templates for tree/branching creation. A customer surfing for Speedtree templates would also see your leaves that are a perfect fit for the Speedtree templates.

You would also want to be active on different areas (e.g. nice art creation/rendering). For example, you would make really nice artistic eye catching renders and ad them on many different places where artist hang out and then make sure you link them to your work here (e.g. popular game forums like polycount, architectural portals, social media, etc.)

You can also use popularity of other artist to bring your things to attention, Pinterest for example is a good tool for that sort of thing, you make some nice pin boards with categories that attracts people in general and then add some content specific pin boards where you add some of your own things.

for example, you could make a board "game vegetation" and ad your leaves somewhere in the middle amongst other nice collected art.

See my pinterest account for example here (https://www.pinterest.com/iterateCGI/) the board "Robot Character concepts" contains one of my creations somewhere in the middle.

You can follow hoe takes it off and pins it to his own boards (so your work spreads out in this way). In the board "Motion graphics design" the same thing, somewhere in the middle some of my own work is added surrounded by nice work of others.

Nice! So roughly what I need to do is make some publicity of my product and make it and myself know in the crow. I found this technique of pintrest realy interesting and easy. I already applied it. About creating new products, I am always studing and growing so I think it won't be a big deal.
Onde again thank you for all this information, it has been realy realy useful. :)