The Dink Network

I think the things you should be most aware of are, as it has been said, putting proper borders on. Also, simply having a few screens going horizonatally along is very boring. If you used borders (like the hills, water, anythin) and made it so the map was a bit more interesting, with trees and stuff, it would look a lot nicer.
Biggest mistake is leaving hardness on for the hearts and potions...it's not a disaster if it's 1 or 2, but on a screen with loads...