While I am teaching, I'm allowed to set out a"tip" can. It is always awkward asking for money, especially when the tickets are already bought and customers have a food/drink bill. One way I have been successful at bringing attention to the tip can is by making mini paintings! I announce at the end that tips are welcome, and if they happen to tip more than $10, they can take a mini painting.
Last night was my 50th event! I did not even announce that, and with only 15 people sign up I was completely shocked when I counted well over $100 in my tip can. Only one person took a mini painting , yet my can had multiple 20 bills and 10 bills. I felt accomplished and proud that I gave everyone a great paint experience and I was more proud of how everyone's paintings turned out!