Cancellation at the last minute

I had this lady that agree with me to hire me to paint in his birthday party event and just the evening before the event send me and email telling me she does'not need my service.
I feel a little upset because was a last minute cancellation and I already arrange the babysitting for my kids bla bla bla; but well we all learn from this experiences, so now I am planing on asking for a booking deposit since this is the second time that I have this situation.
So... how you guys deal with last minute cancellations? or in general do you ask for booking deposit? Do you use paypal or what kind of system recommend?
I am really new in this business and in learning process TKS for your comment guys!

I do require a deposit of 50% for private parties and $50 for corporate ones. I accept Paypal payments for the deposit, but I'm going to start adding a fee for that to cover Paypal's fee.
If I do not have a deposit, I do not go.

That's so frustrating. Sorry to hear that. I think most of us take a deposit to hold a date. I require 30% before they have a guarantee of my time.

Use a contract and get a deposit.

Most of us started out not doing that... but we pretty much all learn pretty soon that you have to.