Deciding to become a professional photographer is an exciting and scary thing: you're following something you're deeply passionate about and turning it into a career, but with that comes a lot of unknowns. This helpful video will give you a general outline from picking up a camera to getting paid.
Coming to you from the Cooperative of Photography, this great video will give you a helpful outline of the steps to finding out who you are as a photographer and beginning to build a business. Of them, I think one of the most important is preparation in every aspect. As the video mentions, even small things like making sure batteries and memory cards are ready to go for a shoot make a huge difference and add up in helping to convey to the client that you're a professional who has complete of your set and/or workflow. Making your client feel like they're in professional hands goes a long way toward building trust and keeping them coming back to you for more projects. Try to be so prepared that you can anticipate anything that might go awry and have a solution ready before it even begins to slow the shoot down.