Let's start with username making.First you find some words that you like or sound cool, and if you can't think of anything start thinking about something that you like in your life.For example if you loved music your whole life you could put something like MusicLoverForever.If you want to make a username with cool words then you just take cool words and just start putting them in an order that you like them in.
Now let's do some password making.This is easier then username making cuz no one can see it and u don't have to worry about how stupid your password sounds just if you can remember it and its a hard password its a good password.People usually make passwords for something they like/love or something that happened in there life.Well you could just do that for your password.