When using phone mode speak in plain English.
Use the correct official phonetic alphabet when identifying. The cute stuff is nice to help remember a call but not for id purposes.
Listen to see if the frequency is in use before you call. If in doubt, ask, "Is the frequency in use your call".
Don't call CQ, just "your call Listening".
Use "Break" only in emergencies.
To interrupt give your call sign between the other stations transmissions.
Acknowledge a station interrupting and turn it over to them as soon as possible. It just might be an emergency.
Have you ever heard the squelch tail? Don't be trigger-happy. Let up on the PTT switch to let someone else in. PTT vs. RTL (Release to listen)
Brevity, be short and concise with your conversations. If you want to catch up on someone or something go to simplex if possible.
If several hams are talking pass it off by saying the person's name or call to pass it off to.
If you wonder if you can hit the repeater, don't kerchunk it. Give "your call testing".
Run on the lowest necessary power to operate, but don't try to call in on a very low power HT when everyone tells you it is unreadable. Increase your power. Ask for a signal report before you go too much further with your conversation. Remember that the goal is quality communications.
Speak clearly, don't key and un-key your rig the instant you start and stop speaking. It takes a few seconds for the system to come up and down.
Ignore jammers, but take lots of notes; the reason they jam is for the attention. Basic repeater traffic priorities

    1. Emergency and Priority Traffic.
    2. System test or maintenance.
    3. Public Service (Skywarn etc....)
    4. Fixed stations should ensure that mobiles and portable
       stations have priority (especially if you can go to simplex).
   5. Fixed stations.
Follow FCC identification rules. You have to do it every 10 minutes but not necessary to start a conversation with a local station.
Remember that nothing is private on the air. If you have something private to talk about use the telephone (on both ends).
Don't think out loud, your mind may be in idle but the repeater could be used during that time.
No need for "no contact" or "nothing heard" or "clear" after making a failed call. All the other stations heard you not make your contact.
Use extreme caution and it is even better not to repeat what you hear on police frequencies over the repeater. There are laws concerning the public dissemination of information from scanners. Informing the Skywarn net that "they are reporting trees down" in a specific area might be okay. Auto-patch
No business on the radio. Ordering a pizza is up to the local auto-patch group.
Cannot be used to place a call to avoid long distance rates or phone tariffs.
When you call a non-ham be sure they know the rules about language, business etc.
Auto-patches can be terminated immediately if they violate rules of the auto-patch.
Station identification must be observed.
Keep the patch brief as possible.
If you are in doubt about the legality of your patch, don't do it.
Cannot be initiated by a non-ham including amateur automated systems. An amateur must be present.