Among the many joys of being your own boss is setting your own rates. I work with many clients, in many different ways. Some are charged an hourly rate, while for others, I set a project fee which includes the discovery/research phase, along with two sets of revisions. On the rare occasion that I'm required to go onsite, I set a flat day rate, regardless of time spent working.
Just yesterday, a client requested my presence for an hourlong in-office meeting, which – by my calculation – warrants a full day's pay. When you factor in the travel time to and fro, the prep and the unwind, the meals on the go, and of course, the shifting of other work and life priorities to allot my full attention to one client on any given workday, it all adds up. If a client doesn't want to shell out for a full day, there's always the GoToMeeting conference call/Google Hangout route, which suits me just fine, and saves them money to boot – but I can't blame my clients for wanting a little face-to-face now and again.
No matter how you charge, it's key to be upfront about rates beforehand so there aren't any surprises when you submit your invoice. That's where the handy dandy Budget Proposal comes in – but that's another topic for another day.