It is totally up to you how formal (dresses, collared shirts, etc.) or casual (jeans, T-shirts) you decide to go. The Pinterest links above have the best of both looks, choose based on what you fee comfortable and confident in.
I always suggest that the moms/women choose their outfit first. Choose something you feel beautiful and comfortable in. It’s way easier to coordinate outfits for dads/kids based on mom’s outfit, than the other way around.
For dads/men, I suggest avoiding hats (like ball caps). For women, stylish hats can be a great accessory that we can use off and on for variety (sometimes can hide faces so that’s why I suggest no hats for men, hats for some for mom). Logos and busy/loud patterns: avoid if possible, because it can take away from your beautiful faces.
Light colours photograph beautifully, light neutrals (whites, beiges, greys), and neutrals in general work well, and you’ll be able see those themes present throughout my Pinterest boards. When possible, avoid bright/loud colours, and avoid loud/bright/busy patterns.
Adding texture with layers can be a great way to coordinate colours and add depth. This could include cardigans, scarves, etc. Items that provide movement (skirts, flowy dresses, longer cardigans) are great too.
I am more than happy to help you narrow down ideas or make suggestions between options you’re choosing between based on what photographs well! Happy to help make this the best possible experience for you.