First, since you’ve recently just started, I recommend looking into drawing tablets if you’re thinking of making art as a career. It’ll definitely help you in the long run as you’ll be able to familiarize yourself with it earlier. I have one that’s around 40 dollars and it’s absolutely amazing. The surface drawing area is huge for its price, compared to wacoms. The brand is XP-Pen.
Next, this is a very broad topic, but I highly suggest learning the proper proportions/anatomy of a human first. This is so that you won’t have to limit your work solely in roblox and have other options. Learning anatomy will also help you out in the end. A few days of practicing won’t do, perhaps a year. The pay out will be worth it. It’s best to start learning when you’ve just started as your mind will absorb the information really quickly.
Second, a good free drawing app is Krita. It has most, if not all the stuff you’re looking for.
Third, it looks okay! The choice of colors are well done and pretty pleasing to the eyes.
Lastly, yes. You’ll definitely be able to take up commissions when you’ve improved.