to improve the height of your bunnyhop
On the approach bend arms and knees slightly.
Throw your weight backwards and as you do kick forwards with you feet to get the front end up.
As the front reaches its highest point throw your body forwards up towards the bars so that you almost touch your stomach with the bars.
From this point, push off on the pedals and jump the back end up and off the ground .
As you do this, curl your toes forward and suck the back end up into your body by bringing your knees into your chest, and at the same time push the bars away from you so the bike levels out.
for 180's
the only secret is to practice practice practice. You want to pull back as you do for a regular hop, but swing the front end slightly to one side as you do. You don't wanto to swing too far to the side because you need to keep your forward momentum,