Cell phones are everywhere now days. Anywhere you look you will find people flipping them out and not following any level of etiquette with them. Cell phones like other aspects of dealing with people need to have a level of respect for others when using.
We have all seen the adds before a movie asking people to turn off their cell phones, well movie theaters are not the only place where such actions should be taken. Restaurants, public meetings and other such gatherings where the sound of a cell phone might interrupt one's enjoyment of the activity should all be treated with such respect. If you are expecting an important call most cell phones have a vibrate setting and you can excuse yourself from the room politely and quietly when it goes off so you are not interrupting anything.
Now when talking on a cell phone in public, try to remember that you are in public. People so often seem to forget that they are not at home when they talk on a cell phone. They use profanity openly in places where there are kids. They will talk about very personal issues in front of strangers, when normally they would be embarrassed to speak of such things around others. And no one wishes to hear strangers talking about such personal issues. The trick is to remember you are in public and not loose focus as to who is around you. Watch your language and think about what you are talking about and if you would be talking about such things so openly without the cell phone being there.
Figure out your priorities. There are times when the task at hand needs to be of higher priority than talking on the cell phone. Driving is a great example of this and is very often over looked in favor of talking on the cell phone. If your focus needs to be on something important, such as driving, then you need to not use the cell phone if it may cause a danger to you or others because it hampers your ability to stay on task. Cell phones keep track of who called, so you do not need to answer the phone when it rings. You can put it aside and call the person back once you get where you are going. If you really need to answer then do it quickly and explain you are driving and will call them back. Safety is more important than having a conversation after all.
When using a cell phone think of how you are treating others. If you are in a check out lane at a store and are talking on the cell phone instead of addressing the cashier, you are showing a lack of respect and are not giving the person the best attention needed in order to help with any problems that might come up. Same with any kind of service. If a person is doing a job for you and you are talking on the cell phone at a time where they might need your input then there is the possibility that you might mishear them and a mistake could get made. In many cases it is in one's best interests to show respect to people and give them their full attention instead of talking on the phone. In general the best etiquette for cell phone use is to be polite and think about others. Simply figure out what you would wish for someone to do towards you in such a situation and do so for others.