Whenever you're socializing a dog it's important that you're able to recognize your dog's body language.
In order for an experience to be positive for a dog they have to be in a calm and relaxed state, otherwise the experience can quickly become negative resulting in undesirable behaviors as an adult dog.
When you are socializing your puppy or dog: - Work with your dog in a calm and relaxed state, or below their "threshold". - Watch for changes in their body language -If they start to show they are stressed or shutting down they are above their threshold. - Step back from the activity, environment or interaction to a distance where they can be calm and relaxed again.
Keep it rewarding and fun - your dog doesn't have to master every environment, interaction, or experience the first time!