To do a bunny hop you...
1. Begin at a slow pace.
2. Lift your front tire up.
3. Once that front tire starts to level out pull up on your back tire.
4. This should lift up your bike and result in a bunny hop.
A misconception that many people including myself tend to do is that we try to lift both tires at the same time. This does result in some air but only so much. By doing the method described above your able to gain much more air much easier.
How high can you bunny hop? Post in the newly added comment system below.