When you first have your idea for an app your mind goes quickly into overdrive. It’s essential that you write down everything that pops into your head, you can edit it later. You need to make space for more details instead of repeating your thoughts over and over to yourself.
The next stage can be more considered and usually follows a pattern.
You’ve probably seen on your favourite shopping or tv website a section which makes a suggestion for something similar to the product you’re currently looking at or for something that people like you have purchased recently.