There are four major parts of a DND game in my opinion. The players, that's you, are the participants in the scenario at hand. The DM, my job is to create and explain the scenario. The rules are the common framework in which we agree on how actions in the scenario are resolved. The fourth is the descriptive narrative. Everything you know about my game is either on my website or from listening to me describe the scenario at hand. It is difficult to do that when people are interrupting over trivial things or just to "have the last word" to someone else.
Speaking of which: common courtesy is a must. Since we are not all sitting around a physical table it's imperative to allow other players, and me, speak without interruption. Sometimes it just happens, and when it happens folks need to stop talking and wait for either me to finish what I was saying or the other player who was interrupted. The rules attempt to sequence things in meaningful way so things happen when they're supposed to. Given that speaking is a free action, a player character can speak whenever they want. But the focus of the game is not on your actions at the moment so don't expect to say your character does anything but talks.
When creating your character it is expected that you read on the website the section on how to create a character; it's that simple. You come across as a fool when you insist you read and complied with everything yet there are holes in your character an npc can drive a truck through. If you choose to not heed the warnings and friendly advice on that page don't get your feelings hurt or think I am being unfair when something bad happens to your character.
I started DMing when a friend I used to wargame with (toy soldiers and measuring tape days) mentioned it and since I had read, "Lord of the Rings" I got elected as the DM. I like creating my own stuff, though at times it is a double-edge sword. On the bad side I have to bend and modify things to fit into my campaign. On the other hand it is not a published campaign world like Eberron where someone else may have read all of the rule books and novels and argue with me who is king of this place or after the ice cream wars only druids are allowed to rap anymore. If you need more information, ask me, the information in the "Races of" or other books may only be being used for mechanics and classes and things, and not how halflings make their beds.
The game is a shared experience, I welcome players trying to do what they want (within the framework of the campaign and rules.) But I will not be dictated to on what is going to happen or how something should work.
Unfortunately there are times when the game will move slow, players may not know what to do, or the plots and hooks I throw may not appeal to the party. Sometimes the focus of the game is on on one particular player character since they are the ones with the proper skills or in the right (wrong?) place at the right time. Don't get bored and try to disrupt the game. Give others the same consideration you expect for yourself. I try my best to be fair in recognizing people to do their actions. I also know I slip up on that at times. Be considerate of others once more. I do not like or want to railroad players into situations. Sometimes that means many prepared dungeons and scenarios are not used and something else needs to be found to do. If you are having trouble discerning what you and the party wants to do: let me know and I'll railroad a bit.
Humor and small talk is how strangers "break the ice" with each other. But the small talk should not dominate the game. Ten or so minutes in the beginning and then maybe when I need to look something up or need to deal with a situation here at home. We're not perfect, I'm not, so I don't expect perfection. I just expect to sit down and host a game where everyone has fun and tries to do what they can in the game.
Don't wear you feelings on your sleeve; and think of how your actions look like to everyone else. Sometimes your actions may seem right to you but when put into the context of the actions in the game are plain wrong. And remember that unless you and the rest of the party are in the midst of a dungeon or walking across the wilderness: there are plenty of townsfolk and other people around. They see and hear too you know.
New players, it is recommended you stick with character classes/concepts from the core books. If you are not sure how the game is actually played, it's best to stick with the basic concepts of the core game before try to build something complicated on an unsteady foundation.
Most importantly: Let me, the DM, run the game and let you know what is going on as far as descriptions of what is happening and resolution to character actions. Don't insist something out of the book is going to take precedence to what I'm trying to say. Don't assume to know my game better than I do. I do not follow many of the concepts and background information in the books. I've got my own campaign and my own ideas and will stick to them, thank you.
If you believe I am doing something wrong, per the rules, I will not take offense if you challenge me on it. But don't get butt hurt if I tell you I am indeed correct in this situation and perhaps something else is in play or you may not understand the rules as well as you think. I am only human and forgetful so I am wrong at times and I know it. But if I tell you that what I said is right in this situation then accept it. It's just that simple.
I do not, nor will I, roll all of my dice so everyone can see them. I willl also not tell you all of the modifiers on my dice rolls that I do make public or the modifiers on YOUR dice rolls. The monsters and non player characters in my game are not right out of a book. They may be custom made to fit the concept I had at the time of creation, or just slightly buffed a bit differently. For monsters that may mean simply that I take away one feat or ability they currently have and give them another. Adding a level of fighter or sorcerer on a goblin right out of the Monster Manual makes a big difference for example.
My game is not for everyone. It is not particularly combat-driven. To be honest it is driven by whatever you the players decide to have it driven by. Dungeons? Wilderness exploration? Urban adventuring in the social circles. etc. It is also aimed at mature players who can handle the aspects of reality in the game. Evil is not evil because the bad guy wears black and has a nasty laugh. Human sexuality in all of its flavors are mirrored in the various cultures and races of the game. The seven cardinal sins are both exploited and warded against depending on your alignment and place in the world. Some game sessions are a great experience with everyone being immersed in the story while others just don't get off the ground due to some of the factors mentioned above. If you have decided not to play with me and the group, thanks for stopping by and the best of luck finding another group that may suit your tastes better.
I ask for people to follow simple rules and be courteous to each other three times. After that I will say good bye and end the session.