Whenever you approach any dog it is best to avoid direct eye contact but keep observing the dog’s body language. Look for changes and remember that if you respond by acknowledging the dog’s discomfort you put the dog at ease when he realizes you understand him. There should be mutual exchanges.
For instance, when approaching a fearful dog, use the body language that a dog who is trying to avoid conflict would use; turn to side, no eye contact, no fast-forward movements, avoid over-head motions. Try to loop dogs from the side, use caution not to startle them, speak calmly and softly, so they are not startled.
Less is more, let the dog come to you. Playing hard to get and acting disinterested can allow the dog to approach you when they are ready. If the dog seeks interaction and you begin petting the dog, stop after 3 seconds initially to see if the dog is still interested in interacting. Often, dogs will seek interaction, then be overwhelmed (in over their head literally), but not know how to break off contact until they are pushed past a threshold. Additionally, if they feel trapped or cornered, they may switch from flight to fight, and bite.
With more confident dogs, remain confident with an upright body posture. Some dogs need to be addressed firmer than others and some will test you and see what happens. Do not fully turn your back or otherwise put yourself at a physical disadvantage. Still avoid threatening motions as some may take it as a challenge. Don’t get into a physical confrontation, even a small dog can do damage and healthy dogs have much faster reflexes than we do. Meeting aggression with physical force can cause the situation to escalate rapidly. Often, the very behavior you are trying to stop is re-enforced.
A common problem encountered in the dog park is a dog that is excessively mouthy, jumpy, or displaying other excitable self-rewarding behavior that escalates rapidly. Some dogs can be easily distracted or interrupted and redirected to a more appropriate activity. An interruption can be a verbal correction (eheh), taking the dog by the leash and giving them a brief ‘time out’, or for more extreme cases banging bowls or spraying water. Anticipate problems and take the initiative to lead the activities. If you know the dog has a habit of jumping and mouthing in the yard, keep the dog focused on you, make him sit before throwing toys, wait for play, etc. Don’t wait for him to misbehave. Do not rile the dog up in play. Take breaks to prevent the dog from getting over excited. If a dog repeatedly gets over the top, leash the dog up and remove from the yard. Generally, I give 1 or 2 chances, then say ‘too bad and leave.