Everyone should be dressed for the weather in clothes and shoes that are comfortable enough to move in and are OK to get dirty. The weather can change quickly so wear or pack layers and bring rain gear if it may be needed. It is a good idea to have a spare set of clothes and shoes in the car in case they are needed.
Each family member needs to have their own full water bottle. Snacks will be helpful for keeping energy up and little bellies happy during outings. Trail mix, dried fruit, energy bars, cheese slices, crackers, and sliced veggies all make good snack options.
In addition to water and snacks, fill it with: sunscreen, insect repellent, hats and sunglasses, tissues, a small garbage bag, and any medication your family may need (such as an inhaler and small first aid kit). Other items you may want to bring are: binoculars, magnifying glass, field guide, a camera, a small container for each child to use to collect nature "treasures", and a towel or small blanket. Older kids may want to wear their own packs too! If you have little ones that may tire quickly, a baby carrier will work better than a stroller unless it is able to go "off-road".
Be ready to have fun, get dirty, and enjoy nature and each other!