The starter is grounded to the engine by nature of the mounting bolts. The main ground wire from the battery to the frame of the bike is the most important. Make sure it is clean (sandpaper or emery cloth) and tight enough that it can't be moved by tugging on it.
http://www.kawasakimotorcycle.org/fo...ing-guide.html
Get a manual. Buy one. Borrow one. Steal one. You shouldn't be allowed to own a motorcycle without one.
If your starter solenoid has burnt tips, you may have a slow starter, though it is unlikely.
Good luck.