Red raspberry leaf tea and evening primrose oil are for softening and making things more prime. You can also buy RLT capsules and I believe some women insert them at night in their lady bits. I haven't done this so I can't attest to it lol.
Sex - both orgasming is helpful I hear. The semen has the right chemicals and the woman's orgasm supposedly helps the uterus contract. Doesn't have to be at the same time, but preferably during the same session. Hahah if that makes sense!
Spicy foods. Think Indian cuisine. Curry! Chili! (I know that's not Indian LOL)
Bounce on a yoga/exercise ball. Or on the edge of a sofa or bed.
Get on all fours. And just stay there. Or wag your behind, clean the floors. Just stay on all fours for a bit.
Walk walk walk walk walk. Uphill, downhill, for an hour, for 10 minutes at a time. Just walk. Sitting down keeps baby relaxed and away from the pelvis. You want him/her to try to engage and so the force of gravity when you're standing or moving helps baby to get into position.
Squats, stair climbing. I don't know why, but it is recommended!
Nipple stimulation. It's recommended for a few hours a day to actually reap the real benefits. It tricks the uterus into thinking you're breastfeeding by releasing oxytocin, and can cause it to contract. Some say this can cause much more painful contractions than what happens without it.
Bouncy car rides. Same principle as being on the exercise ball, walking and squatting. You're causing the baby to attempt to engage and thus soften and ripen and dilate the cervix.
Do NOT attempt castor oil. It is said to help but only because its basically a laxative and will cause you to have diarrhea or vomit, which both can cause the uterus to contract. It is not recommended! You may just get ill and dehydrated.
Stay hydrated!