Learn the guard's name

Every condo and apartment block has a ยาม (security guard, formally รปภ.) at the gate, often on twelve-hour shifts. The guard knows which taxi stand is quickest, when the water will be back on, who signed for your parcel and where the best ส้มตำ in the soi is. Learn their name and use it with พี่ or ลุง: พี่ชื่ออะไรครับ/คะ? A greeting every day costs nothing; a cold drink on a hot afternoon or a small gift at New Year is warmly received. In return, parcels are kept safe, taxis get waved down, and someone notices if you haven't been seen for a few days. Calling out 'ยาม!' to get attention sounds rude; say พี่.