Handling a very small puppy with respect
A young Chihuahua should be handled every day, but the handling must be scaled to a dog who can weigh less than a bag of sugar. Work on a stable, non-slip surface, support the chest and hindquarters whenever the puppy is lifted, and pair paw touches, ear checks, and teeth checks with fragments of food small enough for a tiny stomach. Watch the puppy's signals closely and stop at the first lip-lick or turn away: a Chihuahua who learns that saying no works has no need for the snapping that gives the adult breed its unfair reputation. Consent-based handling now is what makes nail trims and vet examinations manageable for the next fifteen years.
The ground-level rule
The defining socialisation decision for a young Chihuahua is putting the puppy down. A puppy who tours the world from arms or a bag learns two damaging lessons: the ground is where frightening things happen, and barking from a height is how to deal with them. Instead, let the puppy walk in safe places, quiet pavements, friends' gardens, the pet shop at a calm hour, choosing routes where it will not be swamped by big dogs or crowds. Carry the puppy past genuine hazards, by all means, but make walking the default and arms the exception, and the puppy will start to read the world as a place it can handle.
People, without the looming hand
Most Chihuahua fear of strangers is fear of how strangers greet: a tall person bending over and reaching a hand down onto a tiny head. Coach every greeter to crouch sideways, rest a hand low and still, and let the puppy choose to approach and sniff before any stroking, which should be on the chest or shoulder. If the puppy declines, the greeting is over, and that outcome must be respected without disappointment. Meeting people this way, in ones and twos, at home and out on walks, teaches a young Chihuahua that humans are predictable and escapable, which is precisely what confidence is made of.
Children and other household pets
Children meet a young Chihuahua on the floor, seated, with the puppy free to walk away, and never pick the puppy up: small dogs are injured every year by well-meaning children dropping them, and a puppy who has been dropped often fears children for life. Play happens at floor level with toys, supervised throughout. With other dogs, choose calm, gentle companions and protect the puppy from boisterous play that could hurt it, letting it watch bigger dogs from a safe distance before any close meeting. Cats usually tower over a Chihuahua puppy and introductions through a barrier, rewarded for calm, generally progress quickly, with separate feeding and resting places for everyone while the household finds its shape.
Preventing the barking spiral early
A young Chihuahua who barks at visitors and passers-by is usually a puppy who feels too exposed, so socialisation and management work together: let the puppy observe the street from behind a window or gate at a distance it can manage, reward quiet watching, and give visitor arrivals a routine of greeting calmly then settling with a chew. Keep a note of what the puppy has met and how it reacted, so exposures are broad and graded rather than random. Logging each new encounter in KinsLe's Care Teams keeps the puppy's progress visible at a glance, so the next walk can pick a slightly braver route than the last.