What is a good bedtime routine for my baby?

A consistent one. A good routine is one you can stick with always. Simplicity is best, something you enjoy. Usually an evening meal gets things started. A small playtime afterwards can use up any residual energy, a calming bath if it's that night, a story, perhaps another feed, then bed. If you like to sing, then do that. Be consistent, put the child down awake, and they will come to accept and love sleep.
Consistency. Simple to say, but hard to do. Get in a routine with your child. Quiet time, reading time, and stick to it. Once the routine is established keep at it. Erratic bedtimes and schedules can throw a child off and make them cranky the next day.