Since you chose "often", this is a problem area for you since you tend to stop at your first good idea much too often. You need to change your habits in this area, otherwise you're likely just putting all of your effort into executing mediocre ideas. "
It's quite natural for people to stop at their first good idea. But when you do this early on in the creative process you are limiting the possibility of an even better idea materializing. One way to discourage stopping at your first good idea is to work quickly during the early ideation phase and simply keep judgment out of the process. If you don't judge, you don't know what's good or bad, so you don't get attached to the "good", stop ideating and prevent yourself from finding something even better. The reason most people don't come up with "great" ideas is because they come up with "good" ideas.