Tips on Tipping

Tyler Cowen summarizes the research on tipping

Drawing a smiley face on the check increases a waitress’s tips by 18 percent but decreases a waiter’s tips by 9 percent. In one study, waitresses increased their tips by 17 percent by wearing flowers in their hair. In general it pays to look distinctive albeit not freaky.

In a little bit of overkill, here’s a PDF chapter by titled Mega Tips Scientifically Tested Techniques to Increase Your Tips (PDF)

The effects of the touch manipulation were significant. Customers left an average tip of 12% when they were not touched as compared to 14% when they were touched once on the shoulder and 17% when they were touched twice on the palm of the hand. Subsequent research conducted by various other researchers has demonstrated that: (1) casually touching customers increases the tips of both male and female servers, (2) touching increases tips more when waitresses touch the female
members of mixed-sex dining parties than when they touch the male members of those dining parties, and (3) touching increases the tips of young customers more than those of older customers.