Clary sage - I sniffed it int he last week of pg and it gave me strong bh's. So if it works for you and you use it when you are having minor contractions I wouldn't be suprised if it strengthens them.
Moving baby's head down -
Lunges with one foot on the bottom stair.
Walking up the stairs sideways.
Walking with one foot on the kerb and one on the road.
Doing figures of eight with the birthing ball.
My babies have never fully enagaged. DS was high and 2/5 engaged at 4.30 am and was born 4 hours later.