1. Always write them down
That’s it basically. Nothing else is required. All you should need to do is remember it from the time it pops in your mind until the time you put in your notebook. Which brings me to a sub-point or let’s just say:
2. Always have a notebook with you
Any idea, however important it might be, should find some space in your notebook. The sheer concretization of an idea in words involves not just loose thought to run around your mind but puts them in real words which you can follow up later on.
3. Work with your idea
You now have a notebook with ideas, thoughts, sketches and many other things you think about saved and preserved for the future. From now on, you can add, extend and question what you think at another point and develop it.
Usually, when you have an idea two things can happen.
a) You forget it, which happens in most cases. Remembering it afterwards can prove to be highly difficult and a pain.
b) You look it up in your notebook, which should make point a) obsolete since you’re reading this post.
I hope that this post pointed out the obvious and you know just as much as you did before.