Now, on the other hand, if it's something that you might want to act on but you're not sure if you want to do it or should do it, you have what David Allen refers to as a "look into" or "R & D" project. The outcome is a decision whether or not to move forward with, incubate, or jettison the potential project that piece of paper represents. The actions will focus on gathering data that you need to make a decision you can feel good about.
In summary, it's okay to decide not to decide if you have a decide not to decide system, but it's critical to be honest with yourself about why you're not ready to make that decision. If the reason is because you lack data, then you have a "look into" project. If it's because the time isn't right to act, you have a "someday/maybe" commitment.
One last piece of advice. If you really want to trust your project list, you must build in the habit of a weekly review once you get your system off the ground.
Best of luck to you and welcome to GTD!