My only advice is this: stay away from visual jokes. We all use the same characters and backgrounds, so jokes that rely on visual humor don't often work all that well - what makes a funny comic on SC is good dialogue. But that's just my opinion.
Been a while since I've been stoned, perhaps its time to endeavor once again. I sort of grew up with garfield comics, so its hard for me to get away from obvious humor sometimes........
I try to make comics that even Billy the nearsighted-braindead kid can understand.