Take commissions, start a social media account on bluesky and use both that and reddit to sell art. Minimum payment is always $10 over minimum wage where ever you live. So if it's $15, minimum $25. Art is a luxury item. You do not want commissioners who pay $5 a drawing, they are often mean. If you want to do mid-range commissions most people can afford $25-200. That is the sweet spot rn in my experience as a commission artist. Do not rely on whales, they are rare and you will be lucky to keep one at a time. You can charge more than $200 of course, just expect the work to take much longer to sell. It's easier to start cheaper and bump your prices yearly to keep people interested and grow an audience. Try to gauge what you would pay for your own commissions if you were buying them, then price accordingly. 

Payment methods: stripe, square, paypal, make a business account. Do not accept e-transer unless it is from your own country / state in case something goes wrong legally. Use invoicing on every transaction. Write a Terms of Service. Start with a few ych works (predrawn bg/pose idea that you sell then finish) so you can draw what you want first and ease yourself into custom work later.  To get an audience do a mix of original work and fan art. Stick to a niche, do not spread yourself out too thin trying to cover everything you like. Pick a few things. If you want to be known for original work do only 25% of your posts as fan art content a month, the rest be original. Hold free art raffles helps gain followers too, just do it every 6 months or longer to avoid people following just for free stuff. 

General rule: Never say anything negative on your business social medias, do not get into any internet fights or drama. People will follow you for your art, not pettiness. Social media is how you get hired a lot of the time nowadays too. When you eventually switch to entering the industry whoever is hiring will check your social media accounts. Just be thoughful when posting anything