Clary sage can help soften your cervix. Lush sell a bath bomb called Sex Bomb (ironic huh?) that contains it but I'm sure there are other products that do too. Aside from that, castor oil and spicy food. Good luck :)
Eating lots of pineapple sometimes helps. And Raspberry leaf tea.
Lots of sex, walking, pineapples, nipple simulation.... A few I've heard.
Ive heard bouncing and rocking your hips on an excersize ball can help open your cervix. Also wha the above have already mentioned. Hope this helps.