To start out, just make a normal ki or mana ball and charge it up. Next, start visualizing lightning striking down all around you. Actually hear the crack and sizzle of the lightning bolts. Then, visualize all little lightning bolts striking around your hands and striking into your ki ball and causing electric shocks inside and outside it. It would make it even better if you know how to perform some electrokinesis. You will know by the feeling you get in your hands if you have made this correctly. When it's made, blast away.
(I did not create this technique the info above is from http://kinetics.practiceforum.com/t2-electrokinesis-training-tip-s