Labor and contractions are all about the release of oxytocin. Usually it's released by the baby to kickstart the labor when the baby is ready but..

Semen is good for softening and ripening the cervix so sex is beneficial, plus the intimacy and if you climax would give you a release of oxytocin

Nipple stimulation, can be done with a partner or if you have a breast pump do it on the lowest setting.

A warm bath to relax yourself.

Sitting on an exercise/labor ball allows gravity to work in your favor to encourage baby along.

Going for walks.

But PLEASE do not use castor oil. I know research says theres not many negative side effects BUT the research was only done on women who were past 40 weeks, before that it could be dangerous and it's not worth the risk.

I wish you the best of luck and a happy healthy delivery whatever happens if baby comes on their own or if you have to be induced. Either way you're having your baby soon!!! Congrats!