Contrary to popular belief, a wagging tail doesn't always mean a dog is happy. The position and speed of the wag can indicate different emotions. A high, fast wag may signal excitement, while a slow, low wag could indicate insecurity or fear. Pay attention to the context and other accompanying cues to interpret your dog's tail language accurately. 

A dog's ears can provide valuable insights into their mood. Erect ears may indicate alertness or curiosity, while flattened ears can signal fear or submission. Dogs with relaxed, slightly back ears are typically feeling calm and content. 

A dog's overall body posture can convey a lot about how they're feeling. A relaxed, loose body typically indicates a comfortable and content dog. Conversely, a stiff, tense body may suggest agitation, fear, or aggression. Pay attention to your dog's posture, especially in new or stressful situations, to gauge their comfort level. 

Just like humans, dogs have facial expressions that convey their emotions. A relaxed mouth with slightly open lips and a relaxed tongue usually indicates a calm and content dog. However, bared teeth or a wrinkled muzzle can signal aggression or discomfort. Be mindful of your dog's facial expressions to better understand their emotional state. 

While not strictly body language, your dog's vocalizations can also provide clues about how they're feeling. Barks, growls, whines, and howls each have their own meanings and can indicate excitement, fear, frustration, or pain. Pay attention to the context and accompanying body language to interpret your dog's vocalizations accurately.