United States is a very large country. It is larger than Europe and 2.5 times larger than India. From the coast to coast, there are many cities and attractions. You should try to pick one or two areas and visit them. Otherwise, it would become very hectic for you to try to cover everything.
In the US, the waiters are paid very little money per hour. Therefore, they have to depend upon the tips to make their living. Therefore, tips should be considered not totally optional but you should consider giving the tips to them, unless the food or the service was very bad.
There are many public places where smoking is prohibited. Therefore, don’t smoke anywhere you like. There may be designated smoking areas where you are allowed to smoke.
Americans are highly punctual and they usually arrive on time, unless some major reason such as accident or unexpected circumstances arise. Therefore, be on time. If you have to be somewhere at 10 AM or if the show or the attraction is supposed to start at 10 AM, it will start at that time.
You should always observe the traffic signs and laws. You simply can’t cross the street anywhere you like. You can’t park anywhere you like. You can’t park in the parking reserved for disabled if you are not disabled and have a valid placard from the Department of motor vehicles.
Unlike almost everywhere in the world, the US still uses the old system where the temperature is in Fahrenheit instead of Celsius. No meter or liter either. Instead, you use miles and gallons. It might take some time to get used to it.
There are many national parks for the nature lovers. There are many big cities with skyscrapers. There is snow, desert, and beaches. There is something for every one for every kind of interest. Therefore, prioritize on what you would like to see.