People always want to know what to wear for a portrait session and I'd tell you "wear whatever you normally wear" but, well, I've been known to wear some fairly bizarre concoctions if I think I'm not leaving the house and then decide I need to go to the grocery store and there I am in a linen skirt, ratty old t-shirt and crocs and I'd really rather not have myself preserved on film in one of those get-ups. I know I'm a walking "before" picture for a fashion make-over but with small kids and a computer full of backlogged proofing I can't always quite be bothered and if I do there's some odd risks involved in clothing when you have preschoolers. Today I've stepped in chocolate milk and sat in honey. So I'm going to pretend that you are like me and in your daily life wear things that are, perhaps, not QUITE as lovely as you'd like to present yourself and your family to the world.
So...
Newborns: Newborns should be naked. If you have a special, heirloom outfit or a sweet little sweater someone made for you, have it ready. If you have a quilt someone made for you that is important to you, have it ready. Solid colored, lightweight swaddling fabric is good to have around as are cute hats, simple headbands but don't feel the need to invest in anything you don't already have because, well, naked is good.
There, wasn't that easy? Not even any shopping required.
Girls: You should allow her to dress herself and then subtract from the outfit anything you really hate and cannot bear to see on your wall. This IS a portrait of her and her clothing should reflect who she is, not who Gap or Tea Collection want her to be and my goal is to get a portrait of the actual child, not a heavily stylized advertisement for childhood. Be aware that she'll probably be dirty by the time I'm done with her (I do tend to encourage children to play and that messes them up) so avoid anything so precious you couldn't bear it if it got stained. Does she have a stuffed bear she won't put down? Bring it. Does she insist on wearing a tutu over everything, including her snow suit? Leave it. When she's grown up you'll want to remember her as she was, tutu, snowsuit, stuffed bear and all.
OK, you want specific instructions. A solid colored dress made out of woven fabric like linen, not a knit or t-shirt type fabric, with some swing to the cut and some texture. Going a size up often helps with the flow. If you keep it simple the final picture will remain about the child, not the styling.
Boys: Again, the goal is to make a portrait of the child, not a magazine spread, so don't make yourself nuts with the styling. Let him wear what he likes and take away anything you hate. Jeans, a plain shirt and some kind of layering are perfect. Feel free to invest in a new t-shirt - they often tend to get subtly "pilly" after a while.
Families: Unless you tend to wear matching reindeer sweaters in real life, you shouldn't wear them for your portraits. Instead of trying to match everyone lay out all the things you are thinking of wearing and ask yourself if this would work if it were one outfit. Do the patterns go nicely together? Is there some variety? Then you are good to go!
Things to Avoid:
I once, when watching the summer Olympics, observed a man who had just medaled in butterfly, a physically demanding stroke, stand, poolside, in a Speedo. This was before swimmers wore full body suits and he was in tight, underwear like spandex. There was a bit of what looked like a spare tire around his waist and I thought if THIS MAN, who is about as physically fit as it is humanly possible to be, looks less than perfect in a Speedo there is simply no hope for any other man anywhere.
There are some items of clothing that look bad on you no matter how good you look. Some specific things to avoid:
Speedos. You'll freak me out if you show up to your photo session in a Speedo and see the anecdote above about the world class swimmer.
Yoga pants, sweat pants, or any variation thereof. These only look passable on the pretzel chick from your yoga class. If you are a professional dancer, go for it. For the rest of us mere mortals, no.
Polo shirts. They drape in unflattering ways. I know they are comfortable. I know you wear them every day. Don't wear them for your photo shoot. Please.
Khakis. Ubiquitous these days, most of these are designed by the same sadists who make high school band uniforms to look bad on everyone. At least, unlike those marching band uniforms, khakis are rarely 100% polyester but you should still avoid them.
Athletic shoes and Crocs. Big bulky shoes just look lousy in pictures. If it's summer, go barefoot or wear sandals. In winter go for flattering boots.
Giant headbands for the baby with silk flowers as large as the baby's head and an elastic band that looks eerily like a cheap garter. There are beautiful, simple headbands available on Etsy if you have a headband yen.