A crucial mistake made time and time again at dog parks is not removing a dog from their leash before they enter the off leash area. By leaving your dog on the leash you can create stress, anxiety, and fear in your dog or others – all triggers for aggression. Help stop dog fights before they start by allowing your dog to communicate properly and acclimate appropriately to the new social situation. Remove the leash!
If you are not comfortable removing your dog from the leash before entering the park, then your dog is not ready for the dog park. Dog parks are only for dogs that are very well socialized and friendly. It is not a good place to work on socialization because there are too many factors you cannot control, like what other dogs are at the park and their personalities. Try setting up private play dates for your dog until they are ready for the dog park. Set them up to succeed. One bad experience can stick with them for life.