Do

Always be polite regardless of the circumstances.  If not, avoid transmitting.

Set a good example especially for short wave listeners who may be thinking about becoming a ham.

Be a good listener.  It will help you better organize your thoughts before transmitting.

Reply to a CQ, or call CQ yourself.  It helps keep alive the magic of ham radio. 

Speak clearly and slowly, especially when giving your call sign to someone you have never worked before.

Promote friendship and goodwill to DX contacts.  Look for ways to get to know each other rather than simply exchanging signal reports and 73s!

Try to keep track of everyone in the QSO.  Hopefully someone has assumed the role of "traffic director" to make sure everyone has a chance to contribute to the discussion.  If not, don't hesitate to do it yourself.

Make it clear at the end of each transmission which station is expected to transmit next.  Try to do this even when operating VOX.

Operate on frequencies that are in whole KHz (e.g. 18.130 Khz). This alleviates ambiguity and makes it easier for everyone to be on the same frequency.

Openly praise other hams when you observe them doing something that you feel is especially deserving. e.g., helping demonstrate ham radio to a group of scouts.

Always be ready to quickly and calmly respond to emergency situations.  Rehearse what you would do if presented with various scenarios.

Pause between transmissions.  "Quick keying" gives the appearance that other hams are unwelcome in your QSO.

Consider using the Internet to enrich your QSO.    Many hams have developed their own comprehensive websites which you can usually find through QRZ.COM.  

Respect the privileges of hams operating in other modes on the HF bands including those who enjoy AM.

Make a point to try 17 and 60 meters.  Good operating practices are especially prevalent on these bands.

Look for opportunities to "Elmer" newly licensed hams when you hear them on the HF bands.   Welcome them, solicit their questions  and give them pointers on  good operating practices.

Remember that no one country can proclaim to be the leader of the Amateur Radio world.   Likewise, no one country's foreign policy is any more right or wrong than that of another country. 

Develop good operating practices.  You will be doing your part in helping insure the  continuance of our long and proud tradition of self-regulation.

Don't

Act like some sort of Broadcast Radio station.  Your fellow Amateurs  will most likely not appreciate such a blatant display of personal ego.

Acknowledge the presence of deliberate interference.  After all, that's most likely the overall objective of the person doing the interfering.

Be excessively long winded especially when in a round-table discussion and during times when band conditions are changing.

Just talk about ham radio.  Most hams have many more interests.

Operate when you are in a bad mood.   You will be that much more vulnerable to losing your temper.

Overuse Q-codes and other ham jargon on the phone bands. 

Claim or homestead any particular frequency for nets, schedules, etc.  If your designated frequency is already in use, simply move up or down as necessary.

Transmit before first determining that the frequency is clear.  This includes transmitting within 3Khz of other known QSOs.

Break into an ongoing QSO unless you can hear the majority of the participants.

Ignore someone new to a round table QSO.  We should all do our part to make everyone feel welcome.   Avoid making the discussion appear exclusive to your particular circle of friends.

Test your transmitter over the air.  It is far better to use a dummy load.

Cough, sneeze or clear your throat into your microphone.  

Operate VOX except when in a QSO with three or less participants.  It tends to foster "quick keying" which may give the appearance that you don't welcome  breakers.

Become a "Band Policeman" quick to tell others what you feel they are doing wrong.  In instances where it may be called for, always be polite and constructive.

Turn up your microphone gain or resort to excessive speech processing in order to be heard.  Such practices will most likely result in diminished audio quality and increased likelihood of interference to nearby QSOs.

Use the word "break" when wanting to join an on-going QSO.   Simply give your call sign between transmissions and reserve the use of the word "break" for more urgent situations.

Join an ongoing QSO unless you have something to contribute to the discussion.  It is especially rude to interrupt  other hams with a  request  for audio checks,  signal reports, etc. 

Operate in any fashion that is not in keeping with good amateur practice.  Be certain to always comply with the provisions of Part 97 of the rules.

Knowingly interfere with an ongoing QSO just because you are working DX, especially split frequency. 

Say that the frequency "is not" in use when you hear someone inquire.  Refrain from responding at all unless you know for certain that the frequency or one nearby "is" in use.

Ridicule other hams or express any negative views of the overall state of Amateur Radio.  If you don't have something positive and constructive to say, avoid saying anything at all.