How to Optimize 3D Model to sale on Unity Marketplace

I just created a Daniel defense gun 3d model in Maya and textured in substance painter. I upload this 3d gun on CGtrader. At CGTrader, it’s sold and I receive a 5start rating from the customer.

I am creating 3d model for games, so I think , unity marketplace is good for me, but I don’t know unity, can anyone tell me, how to optimize my model to sell on Unity Marketplace

I have great weakness in 3D Modelling. I have been search for a good source to learn and educate myself. Thanks!