Admission and parking are free. Dress comfortably, put on some sunscreen, perhaps wear a hat to protect yourself from the sun. Wear shoes you feel comfortable strolling in. The festival covers several city blocks, so you'll be walking a lot. Consider backpacking children.
Strollers take up more space and are difficult to navigate through crowds.
Bring along cash for food and beverages. None of the food and beverage vendors accept credit cards. Don't fill up on food at the first food booth you see. Stroll around a bit to get a flavor of the offerings, then sample several of the dishes that appeal to you. Be careful with your consumption of beer and wine.