a) Am i solving a problem people REALLY do have?
b) Does the problem, require an urgent solution?
c) Is the solution feasible?
d) Is the solution easily copyable for competition? if it is not that's great, otherwise...
e) Can I evolve the solution overtime? meaning even if the competition copies the idea, they don't know what the next step in the evolution of the solution is so I'm always one step ahead of the competition even if they copy my ideas?