Use your good ideas.
Just don't give away the rights to your creation. Make sure that you can re-use your story and elements.
I've seen countless stories about people who made a wonderful classic early in their career. (I'm talking about creators, and not necessarily writers specifically. Could be writers, game makers, etc.) Then later in life, they decide to repeat their story, updating it to reflect the newer "modern times". Then later in life, Hollywood loves their creation and wants to make a movie using the nostalgia of these old things, and other people are involved in creating the new feature, but the initial creator still gets to authorize this idea and give his or her blessing on the new project.
In other cases, the main character ends up being used as a template for another story. Often I've read about how beloved heroes were just an evolution of the ideas that someone had when they created an earlier character.
You may end up creating another character for the story. Then you might always remember that other character, who may end up being useful for some future work you get involved with.
So, use up your best ideas, and see what works and what doesn't. If it doesn't work, you may be more likely to see an actual problem, instead of blaming your artificial limitation of using less ideal stories. After your creation becomes the most awesome thing ever invented, or after it doesn't, it can still be a good basis for you to be able to draw upon later. And, if you do decide to draw upon your earlier ideas in this way, it will be better if your earlier ideas are more fleshed out. Then you can easily tap into what worked well, or immediately start making changes and head off into a new direction, instead of wasting time much later in life (by learning the lessons that your earlier experience could have taught you).