When you are waiting at the bus stop, you should wave to the bus driver to indicate whether or not his is the bus you want. The proper wave to use depends on where in the world you are. In the US, the "negative" wave (e.g., you don't want this bus) consists of holding your hand out at waist level, palm-down, and moving it back and forth in a right-to-left motion. The "affirmative" wave (you want this bus) is essentially the same as that used to hail a taxi: finger pointed to the sky in the general direction of the bus. In London, you indicate you want the bus by pointing your finger straight out towards the street.