Onboarding is where most first-time app builders put their effort in exactly the wrong place: a carousel explaining features nobody has seen yet, followed by a sign-up wall, followed by an empty screen.
Let people reach the point before they sign in
Whatever the app is for, there is usually one action that demonstrates it: add the first task, scan the first receipt, play the first round. Put that before the account, and ask for the account when there is something worth saving. The prompt box on our own home page works this way — you can type your idea before you have an account, and it follows you through sign-in.
Ask for one thing per screen
Every extra field is a place to stop. Name and email are usually the whole list; anything else can be asked later, inside the app, when the reason for asking is visible.
Never show an empty screen
A new account looks like a bug unless you fill it. Either seed sensible example content clearly marked as an example, or make the empty state a single instruction and a button. When you generate an app in Buildr, ask for the empty state explicitly — it is the screen the most people will see and the one that is most often forgotten.
Say what happens next
After the first real action, tell the person what changed and what to do now. "Saved" is a fact. "Saved — add two more and we will start the weekly summary" is a reason to come back.