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.
Lots of sex, walking, pineapples, nipple simulation.... A few I've heard.
Eating lots of pineapple sometimes helps. And Raspberry leaf tea.
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 :)