This is what I do when I draw art for my game:
1) Hand draw and scan it in. 1:30 hours
2) Open up in your image editor (I personally use GIMP) and instantly re-size it to the correct ratio. 15 seconds.
3) Use that lovely Line Tool to trace the outline for everything. Since you have a background as well, you would probably be better off tracing the character on a different layer. 45 minutes.
4) Now, if the character is still too thin, you can re-scale the character without messing up the background. 10 seconds.
5) Color. Because you're working with a smaller image, it's much quicker to color and shading is easier as well. Still a lot of time, but you can get it done quicker. Then again, I suck at shading, so it'll probably take you much less time.
Hope that helps.
EDIT: Then again, I'm not exactly the best artist myself. Take what I had to say with a HUGE grain of salt.