When someone invests in your business they aren't actually investing in your business, they are investing in you. It's good to keep that in the back of your head.

From that point then when they say "go prepared" it probably means in relation to how well you know the person. If you're asking your super rich Uncle, you probably don't need too much more than a good idea and a smile. If you're asking angels, then you want to impress them. You want to convince them that you are a "winner". An amazing pitch, an amazing product, knowing all your numbers, already have raised 10%-50%, those are all things that impress.

So when you are thinking about getting prepared, you want to do whatever you can that you think is going to impress the person you are pitching. For an experienced angel/entrepreneur that will probably mean knowing your numbers super solid & have a bunch of great charts/examples.