I'm sure that's easier said than done but if you're new to modeling and have a photoshoot coming up, it's important to keep your stress level to a minimum. Some new models are all thumbs and tend to over react when trying to figure out how to prepare for a shoot. Photographers are very understanding people and if you're new to it all, they won't expect you to be a pro. If you have questions, ask them and make sure you understand what is being asked of you. To get the best results, you'll all have to be on the same page.
When in doubt about wardrobe, bring more. It's easier to choose from more clothing options than less. Ask for references like certain brand names or styles and look them up online to get an idea of what look the photographer is going for. Make sure to find out if you need to do your own hair and makeup or if there will be someone on set to do it for you. The photographer is there to help you so don't be shy about communicating with them.
With practice you'll come to master preparing for a photoshoot. If you're anxious or stressed out, don't run around like a chicken with its head cut off. Take deep breaths, contact the photographer with your questions, and make sure you prepare everything a day before the shoot or the night before at the latest. Avoid packing everything the morning of because chances are you'll forgot something. The less stress you have, the better your complexion will be, too.