As the client want to be as comfortable as possible try thinking of 12P in your city and what the weather is like and if you would like to be out in that weather. If not choose either a later or earlier time. Sticky skin is not something I want so I always try to aim away from mid day outdoor sessions. You also have to factor in weather changes, unfortunately weather is unpredictable and can change on a whim always have a back up location available.
Decide if you want a night time shoot or a day time shoot. Day time gives you all of the color & vibrance of the world. Night time gives the feel of romance just be prepared to have to deal with flash. Of course you wouldn't want your family portraits done at night.
With daylight savings time you have to factor in the time change when scheduling your session. Most photographers can work around your schedule but can also give you the best times to shoot your particular session so just ask.
The days of piling into a box at your local retailer and looking at the cheesy backgrounds are somewhat over. You have the opportunity to get uniquely creative with your portrait sessions and it is well worth it.
Do you remember the days of the laser treatments in the background of pictures. Sheesh what were they thinking?
Professional make up helps your session tremendously, I repeat tremendously! Now I don't mean that you should cover your beauty marks or anything that makes you uniquely you. But professional make up enhances so much of what is already there, that it makes the images as well. It brings out your eyes, and enhances other beautiful parts of you that you wouldn't image were just as beautiful.
If you are the coordinating with family members just make sure there isn't too much of the same color at once. For instance put a bow on your daughter, colored pants on your son, colored tie on your husband and a colored shirt on you. Make sure everything is ironed out, pressed, etc. I would say your Sunday's Best if possible.
I am totally a grump if I don't eat. My advice is to keep a granola bar, or a snack ready for the kids and adults (in my case). Make sure that everyone is well fed, but not stuffed because you don't want anyone (unless it is a baby) to fall asleep prior to your session grumpiness ensues. You should make sure that everyone will be awake and roaring for about 1-3 hours depending on your session.
The week leading up to your session make sure that everyone is well rested, clear your mind, get a massage, do things that relax you. The last thing you want is to seem tired during your session if children are involved you will definitely need some energy. If you are not feeling well let your photographer know that you may need to reschedule some photographers require at least 24-48 hour notice. We do know that unforeseen circumstances do occur so as soon as you are aware of an issue, let your photographer know.
Are there any tips you think I am forgetting? Please let me know in the comments.