If this is the first time you have worked with a photographer it can be a little overwhelming trying to manage a photographer when they are working with your design or fashion line. You are the one that has employed them, but like yourself, they too are an artist and will take structured criticism and guidance but it is wise to not tell them HOW to take their pictures just express to them what kind of pictures you would like, and always ask them for feedback as well. Now, if they are not open to listening to your guidance or suggestions you will want to sit down and have a conversation with them about your expectations.