I tip 20% or more.
When I waitressed, I would aim for 30% of my total sales in tips. Little things help a lot- eye contact, full attention to each customer for a minute, but not spending too much time with them and abandoning the other customers, always keep that drink full, or offer to fill, always come back within 5 mins of serving to verify if everything is OK, and always clear plates quickly once they are done - by asking if they customer would like them removed, and having them hand them over. 
Some people like to sit and chat, which of course ties a table up, but I make sure to keep on filling their glass and smiling, and usually get rewarded with a higher tip that covers the lack of table turnover. I'd have people "hide" tips if it was a large party and the host didn't tip "enough" for their liking, and I've had other tables over tip if they saw good service and someone give a small tip. No matter the tip, I kept a good attitude, and it reflected in my tip jar 
For pizza, I tip 20% as well. We have one Hungry Howies that serves the area, and I've found we get really good service now 
 Everything shows up piping hot.
I can't remember if the "Chic" tracts question was answered - they are given by adherents to some sort of Christian denomination, Jehovahs Witnesses maybe? Rather than tip, they leave a small pamphlet about Jesus. I just put it in my pocket, shrug, and go on my way. I had one lady that always gave them, and I always treated her well....because the tables around her usually saw it, and they would often over tip to cover it. I didn't mind. In her eyes, it was important to leave that instead of money, and I appreciated her concern regarding my soul (though I'm not Christian!) Some of the folks I worked with would complain about it, but I just would keep in mind her intention....though I sure wouldn't get far if everyone's intention was like that! I prefer $$$!