There are a variety of ways to cover your expenses. It can be a game for some, but usually it comes down to:
1. First hour charges greater than your usual rate.
2. A Service or Travel Charge.
3. A Diagnostics Charge.
4. A Minimum Charge.
5. A combination of the above.
What we all want to avoid is that situation where you charge by the hour without these other charges. You have an hour round trip travel time, work on the job an hour, and you've just made half your rate. If you add in a free estimate or bidding time you might make a third of your rate.
Dave