What should you do with a good idea? First, you should take the time to think it through and carefully ponder upon it. Then after you have considered it, contemplated upon it, and perhaps refined it, you should do some additional research on your idea to learn more and to take it even further to the next level.
After all, just because you thought carefully about your idea, doesn't mean it's original or new or even good. It might or might not be. While doing your research you should be able to determine whether your new idea is really something new at all or just pretty much a copy or a tribute to someone else's idea. Still copy or not, a good idea is a good idea.
Further to that effect, you should want to take your idea and get some feedback from people or persons that you respect and that would be knowledgeable about your idea and its prospects. Their feedback could be invaluable in developing the idea further or in seeing other perspectives that maybe weren't apparent to you upon your initial thrust.
A collaborative effort has many advantages and not that many disadvantages. It would still be your choice as to whether to work with others or to walk away, but it is better to have that choice than not to have it, because just one so-called small improvement upon a good idea could have massive implications to the positive.
A good idea should then be tested and re-tested, looked at, and refined as necessary. Although it's nice to have the luxury of 'winging it' -- why not take the time to develop the idea before you test it to see if it flies. After all, an idea ill-prepared, is an idea that will probably fall flat on its face and while we can learn from our failures, it may also discourage us from going further if we test something too prematurely.
As Edison wisely said, "Many of life's failures are people who did not realize how close they were to success when they gave up.” So giving up on a good idea is not something that we want to do. Sometimes an idea must be pushed aside for a bit because we have hit a barrier which we believe to be impenetrable but if one allows their mind to still contemplate upon it, success may yet come.
Good ideas are far too invaluable to let go. When you feel an idea tugging upon you, urging you, whispering to you, you should listen to that still small voice and act upon it. After all, if you close your mind or refuse to listen to your ideas, that stream will dry up on account of inactivity.
Ideas, like life, are a two-way street. You learn by listening, interacting, thinking, pursuing, trying, working, and by giving focused attention. When a good idea comes into your head, it's like Opportunity knocking upon your door. Get up, stand tall, and open that door.
You'll be glad that you did.