It is very important to capture those ideas in any form you can when you have them, even when they might be rough quick thoughts. They do not have to be perfect, but capturing them is a must.
From a few simple words, or a sketch, to a couple of lines of text. Capturing even the beginning of an idea has to be a priority for you.
iOS Software I use to capture notes
Moleskine Flow for iOS
Penbook for iOS