The thing with commissioning, is that you need three things:

1) A Following
This one is possibly the most important part of commissioning here - you need to make yourself visible. Do a lot of art trades / requests to improve your art, and eventually you'll become "famous", and people will be more willing to commission you because it's by you. This is important because sometimes it overrides whether or not you're better than the next artist - someone would prefer a Picasso to Joe Streetpainter, for example.

2) Swiftness
When the commissions come in, they will come in thick and fast. You need to be able to do commissions within, say, a couple of days, to maintain a good reputation for speedy delivery. You can't spend months procrastinating on your drawing, because people won't come back if you do that. Practice drawing quickly, but at your best. You need to meet deadlines, so set them for yourself. You don't have time to waste spending 6hr+ on a single commission.

3) Sellable Presentation
Lastly, you need talent. You need to appeal to your audience, and with it you need to make it look good. Without this, you're nothing, or at least you're berated by your peers. This shouldn't be a problem, as you're pretty good, and once you've gained a following you should be able to gain commissions easily.

Heck, I wouldn't even consider starting commissions until I'm totally sure of myself. (Personally, I don't think I'm good enough.)

So yes, remember, Popularity, Punctuality, Practice :).

Eh, I'm probably not ready yet, then. I lack both popularity and swiftness. Especially swiftness. *looks at multiple pictures of his that took over 6 hours to create*