For my one-on-one training, I ask for a pre-pay for initial packages of three sessions which includes the assessment. This is my ‘getting to know you’ arrangement. After that, I bill my clients based on the number of sessions they had during the month. I have done this for all the time I have been in business, and it worked well for that scenario.
When I teach MELT in small groups as a course of six sessions in length, I have them pre-pay for the entire course, and if one person does not show up for one of the sessions, then this session is forfeited. However, I only teach few of theses courses per year, and most of my business is individual training.