Tips are bonus for an employee who cares about doing the job well. So take a minute now, and before you tip, to consider what good service is and when tips are appropriate. Good service should be attentive without being intrusive. A good server speaks clearly and pleasantly, deals with questions in a positive and enthusiastic manner, yet shouldn't be overly familiar with the customer unless the customer encourages such an interaction. A good server also acknowledges and sincerely apologizes for a mishap or a mistake in service, and offers to compensate for the error.
Service dictates tipping.
And remember good service isn't a saccharine voice and smile. That's demeaning to both the customer, who's being treated like a dollar sign, and to the server, who's dishonestly portraying themselves, and is behaving insincerely.