A kickflip is when the fingerboard flips once towards you, while a heelflip is when the fingerboard flips once away from you. It is a very hard trick to perform at will. This is how to do it more often.

1) Place your rear finger on the tail on the edge closest to you. Do the same with your front finger on the nose. (do the opposite for a heelflip)

2) Ride off the lip at high speed putting full pressure on the edge of the fingerboard.

3) Allow the board to flip and catch it when it is done. (See hardflip for instructions on catching tricks)

4) Land softly

5) Practice, practice, practice.