You could try any or all of these:
Raspberry leaf tea 4 times a day (strengthens uterus)
Primrose oil on cervix (helps soften and dilate)
Walking (helps baby into good position, puts pressure below and stimulates relevant muscles)
Eat pineapple apparently (helps soften cervix)
Sex (prostaglandins in semen help to soften cervix - although, as gross as it sounds, it apparently has better effect when taken orally... Lol, probably a guy just made that up)
And lots of good positions, kneeling, getting on hands and knees and swaying or rocking, sitting on gym ball (these are all good labour supports too, but help before baby is due as well, to get it into the optimal position for travelling the birth canal easiest).
Basically the closer your body is to natural onset of labour, the better it will respond to induction!