I recently tried my luck by making some quick pixel art anime pictures (see thumbnail) and posting to opensea.io in hopes that I would sale quick and make some dividends. Boy was I wrong. I knew nothing about gas fees or how these other NFT groups became so successful. Until I started promoting myself on twitter trying to win free Ethereum, No crypto in wallet so I could not get the ETH (Gas Fee) So I had to go to a polygon (Matic) Faucet. And, that was just so I could post an actually sellable piece of art on opensea.io, they do offer gasless minting which is cool, but I don't think that it is sellable until you create the listing and pay the gas fee up front. Nobody wants to pay gas fees and pay for a $30 painting to boot. At least in my experience. Most NFTs like I said will get backers to invest in the NFT drop, Thats what pushes the value of the digital artwork. Now that isn't saying you cannot find someone out there who will appreciate the work. Because I see all sorts of sales happening on opensea and mintable daily. I can tell you this though, You aren't going to break the bank overnight with one painting and chances are you'll have to pay some kind of currency up front to get your stuff sold.
Don't make the same mistake I made and dive in headfirst without doing research. Promote, Get investors and make a social media presence as vast and as quickly as possible. THEN, drop the artwork and see it flourish. Twitter is a great way to connect and I have promoted myself endlessly with no luck yet. More to come and hope ya'll like the thumbnail I made it myself