had a customer ask about what they should bring as a new player to a game. It is, of course, a good idea to find out what game is played and the average level of the characters. Bring your own dice, pencil or pen, rulebook (if you have one) and pre-generated character. Bringing your own character means that the players and DM do not have to spend game time waiting for you to create a character. Also, make sure that your character is created from readily available mateirals. If you are playing in a D&D campaign, only use the Players Handbook to create your character, until you learn what the DM wants in their game. Brining in a character that you created using source matieral that you found in the internet often results in a character that does not fit into the campaign.
Sticking with the core rules also means that you do not bring in a race that the DM does not have in their campaign world. Not all DMs allow all character classes or races. it is the DM's world and you need to make sure your characger fits in, at least to start. Once you become more comfortable with the DM's style and they get more comfortable with you, then approach about brining in that cool variante class or race you found in the Tome of Beasts on or EnWorld.