Don't throw the butt on the ground! Instead, make sure to put out your cigarette on a non flammable surface (a rock, concrete, sole of your shoe) and throw it into a trash can. Make sure the cigarette is not producing any smoke anymore, as to not set anything on fire. If there are no trash cans around, take the butt with you and throw it away at home.
In a similar fashion, don't throw cigarette butts in flowing water or manholes. Doing this pollutes the water and the environment.
When smoking, don't blow smoke into other people's faces. Non-smokers are the majority, and second hand smoke is dangerous to everyone. If there is someone around you, turn around. If it's windy, move so that the smoke won't blow directly towards the people next to you.
If there is a person with a baby stroller or a toddler coming your way, pause or hold your smoke. Tobacco smoke is especially harmful to babies and toddlers.
If you are out with someone and you want to smoke, ALWAYS ask for permission, even if the person has given you permission before. Not everybody wants to expose themselves to second hand smoke - they may be asthmatic, trying to quit, or perhaps they simply don't like the smell. All of these reasons are valid. (If you want to be extra kind, reassure them that it's okay to say no.)
If there is an ashtray available, use it! This is usually the case in outdoor seating of cafés and restaurants. If you would tip your cigarette on the ground, or leave some ashes on the table, the wind might carry these ashes into food and drink, which is unhygienic, and it also Tastes Bad (trust me on that).
Don't smoke at public transport stops. This is considered rude in many places, and it goes hand in hand with the fact that non-smokers are the majority and they don't want to expose themselves to second hand smoke.
Respect non-smoking areas. If you are unsure whether you can smoke in an area, look out for pictograms, or ask people in charge. Again, non-smokers don't want smoke.
Last, but not least: if you vape, follow all the rules that apply to cigarette smokers, too. In my country, the restrictions for cigarette smokers also apply to those who vape, and I think it's for a good reason. Vapes are also bad for your health and the health of others. Vape smoke also harms people around you and it is not pleasant to everyone, even if it smells nice to you.
