Shaleton West Marches
Bring some basic supplies
You should come prepared to sessions. That means bringing one copy of your character sheet, at least one pencil with an eraser, and a set of dice if you have them (otherwise you're welcome to borrow from the DM for the session).
Be a team player!
Communicate! Tell others (especially the DM) if you feel you are having issues. Be inclusive. We're all in this to have a good time, so share that fun. Nobody benefits from one player being intentionally disruptive.
Likewise, try to see the difference between working with the team and working just for your own goals. Since you only have a limited time to complete objectives, be conscious of decisions that involve splitting the party.
If you have an issue or you feel unfairly treated, talk it out. Speak to the DM and any other players involved.
D&D can seem really complicated at times and everyone's going to get mixed up or have to pause to figure things out now and then — especially when first learning the game. Do your best, though, to stay on top of things when you can. You should know what your character is capable of doing in combat, for instance, and you should try to plan ahead to your next action during other players' turns. Failing to pay attention to other players' actions will make them feel less important and it will further slow down gameplay.
Where possible, the DM will refrain from making decisions for the players, especially with regards to the distribution of wealth. It's up to you as a party to determine how you will handle sharing income and magic items. It is assumed, unless a party specifies that they would prefer it otherwise, that players acting together intend to share gold relatively equally and intend to distribute discovered items based on need. Hoarding gold or items to oneself detracts from others' experiences and leads into issues of Player Conflict (described below).
Party Conflict and Disruptive Behavior:
There's a distinction between harmless fun between characters (i.e. drinking games, minor pranks, friendly competition) and player conflict that damages players involved (i.e. stealing from others, fighting other player characters) and it is the DM's purview to draw that line. Players who repeatedly or blatantly engage in behavior at the expense of others will be asked to leave the game. The same goes for players who intentionally endanger their party members on a regular basis or who willfully disrupt activity at the table.
All players are encouraged against using knowledge from outside the game while playing in-character. Information relayed on the forums or in discussion between other players is fair game, since it's assumed such information is being shared publicly in the game world, and there is a degree of leeway based on the availability of some information in the game world (i.e. myths about Vampires may very well be the same in-game as they are in our own lives, so it's not unreasonable to guess whether a creature you're encountering could be a Vampire based on its look and abilities). That doesn't guarantee the accuracy of such information, however.
It's also worth stating that most monsters encountered will be altered from their appearance in the Monster Manual (i.e. changed resistances, different HP and damage values, different abilities, different physical descriptions, etc.) and many discovered items will be DM-created or altered from their appearance in the Dungeon Master's Guide. Most of these changes are being made to better suit this campaign, itself, but as a result metagamed knowledge may not be reliable.