Some of my recommendations:

* Ask yourself what would kill the idea, or the category it's in. Sometimes this leads us to come up with entirely new, even better ideas. Often it leads us to come up with a few better pieces to your original idea.

* Ask yourself what the simplest solution would look like for the user in an ideal world, then what the best technical solution would look like under the hood in an ideal world, then how you can marry the two in this world.

* Workshopping the idea with others can lead to totally new developments on the idea as you understand the problem you're solving better, what people think their solution would be, what people think of your solution, etc.

Not GP. Try out the competition. You'll find yourself coming up with many ways to improve their service.