respect
The whole of town is considered to be sacred, so whatever rules generally apply to place of worship in India, apply to the whole of town.
Smoking in public is prohibited by law though the rule is never enforced enthusiastically.
Consumption of liquor or meat is not allowed in the city, therefore it is advised to respect the rule and not carry any liquor/ meat with you while travelling to Pushkar.
It is advised that the men wear full length pants and t-shirt/ shirt and women wear full length clothes. Do not wear off-shoulder tops or shorts while roaming within the city.
Take off your shoes at stairs if you are going near the lake.
Be polite, but do not be pressured into making any offering at the ghats. It is not mandatory.