The second most important thing when talking about professionalism is punctuality. The cliché time is money, is cliché for a reason. Time is money when you are shooting if the daylight is a factor, or perhaps you are shooting an important person. Always be respectful of your client and subjects’ time and what it is costing, as this will affect your chances of gaining repeat business.
Your time is your money. Be punctual for yourself. How long it takes you to get the shot affects your costs, as well as the volume of quality work you can produce for sale. This ties into the consistency conversation. Developing your style and knowing what conditions you need to produce your best work most often, will save you time and make you money.