I'm of the opinion that your goal should be to sell your time for at least your local cost of living's minimum wage. Fuck what the law dictates the minimum at: what sort of hourly income would you need to cover all of your costs if you worked 40 hours/week? (That sort of calculation may seem ridiculously idealistic, but fuck me I'm an idealist. That was the USA norm if you rewind the clock fifty years.)
If you've just started, sure, sell yourself at a discount to adjust for the quality of the output. At a glance, your perspective needs practice, and the faces seem like they're fresh from a "how to draw anime" book. (Maybe you want to draw anime. In that case, it's a lesser concern.) You'll always be able to find fault in your own art, but once you can confidently say "Yes, I know how to art", start charging as if you're trying to make a living from it. (Even if you don't plan to.) You're not just making a dollar, you're signalling the value of the work you put in, and by comparison, the value of all artists. Don't set bargain basement rates just to fill your inbox.