Only tips I have is to draw as much as you can, do artist studies and and take life drawing classes. Practice practice :3 As far as digital goes, again, artist studies are good to try, otherwise, you just have to play around with a program and get comfortable with it! Maybe look at coloring tutorials online.
I think its a good plan. Plus you gave people idea of whats going be on sell then last time. Last summer it was more surprise this art work will be on sell. Give People a reason to think an see if they want it and save money hehehehehe.