Solids over prints.
You can't go wrong with solids. Yes, prints can look amazing, but bold prints can look busy and distract the viewer from the focus of the photo (you!).
Go with some color.
I love nice bold, rich colors in a photo. Wear colors that stand out, but aren't too distracting. Wear a color that you feel confident in.
Don't be too matchy matchy.
For family portraits you don't have to be dressed identically. Color coordination is key, dress to compliment each other.
If you know you're going to be doing a lot of walking, playing with the kids, etc. on your shoot, be sure to dress comfortably. If you've got a new pair of heels that you've never worn, it would be a good idea to bring a pair of flats. Remember, if you're comfortable, you'll look and feel more confident. Which definitely translates to a beautiful photo.
Think about the weather and location.
If we're outside, be sure to dress appropriately for the weather. You don't want to freeze or be too hot!
Most importantly, be yourself! I want you to feel comfortable and confident. The focus of the photo is you!