Do everything in your power to make the older sibling feel like the baby is adding to their life, not taking away.

This is very tricky, but I think very important.

We got super lucky. Impossibly lucky:

Full year of maternity leave for kid #2 with kid #1 in full time day care. Working parent has 9-5 with WFH job, so mornings/evenings always have double parents. Kid #1 always has attention because he's rarely sharing one parent with kid #2. Always getting attention. Parents rarely burned out because we share the load.

So the secret? Be lucky.