So you've taken the tremendous step of finding a role-playing game group to join, and are ready for your first session. What do you bring with you? What do you leave at home? How much is too much?
The venue you're playing at can affect your social and behavioral expectations (it's probably a little easier to show up in costume at a convention than at someone's home), but there are certain essentials that you should probably be packing. The following are my best guesses of things that will help you be prepared for the game, and successfully engage with both the game master and your other players.
1. Your Character
Unless you are making characters at the time of the game, you should have a completed character that is ready to play. Little things that are setting specific can be figured out at the table (where is your character from, are they friends with other adventurers) but you should have the statistics and numbers filled in on your character sheet. The Game master (GM) will probably ask to see your sheet, and be prepared for a quick question and answer session. The GM isn't trying to trip you up, but they are doing quick fact checking to make sure your character is complete and ready to go. If you are making a new character at the session, it would not be an unreasonable expectation for you to have a blank character sheet.
2. Writing Utensil
You are going to be doing a lot of writing through out the course of the game, and you should have something on hand to write with. What you write with is entirely up to you, but i would encourage you to grab something that you can erase. Hit points can change frequently over the course of a game, and you will probably want something that you can erase and replace rather than scratching something out. Your choice of writing implement is up to you, but if you are bringing a pencil that has to be sharpened, either bring a sharpener, or lots of pencils.
Chances are, your first role-playing game will require at least one die to serve as a random number generator, and its possible you will need a bunch of dice. Most players won't mind you borrowing their dice for your first session, but there are exceptions to this rule. Some people are very superstitious about dice ( I personally bought new dice every time i went to a warhammer 40,000 tournament) and a very simple misunderstanding involving you touching another player's dice may cause stress that you didn't want for your first game. I would recommend you get a starter set of dice for whatever game you're playing (the normal 7 die polyhedral set for most games can be handy, since most games use the same dice). Pick a color you like, and go to the dice shop.
4. Scratch Paper
Basically, you'll need something to write notes to yourself on. This can be as easy going as a small post it note pad to as complicated as a leather bound journal. Your mileage may vary, but the primary purpose of having something to write on is to help you keep track of the session. Some characters thrive on notes, others may find them less necessary, but having a resource to write things down on can help you keep your character sheet clear and easy to read.
5. Game Manual
You should have a copy of the player's guide or handbook (alternatives that contain the rules you'll be using for your character are acceptable) for the game you are playing. Having to borrow the book form another play can slow the pace of the game down, and reduce your overall enjoyment. It would also be a very good idea to both make sure you know the rules that pertain specifically to your character, and to be able to find the rules that you use occasionally quickly. You don't have to know every rule in the game, especially at the start of your gaming experience, but you should understand the basics of how characters interact with the world, and how your specific rules work (If you're a spell caster, you should know how to cast your spells, and what they do).
Yeah, i edited this because the number 6 i used to have left a funny taste in my mouth.
Honorable mentions for things that could be helpful, depending on the game you're playing
a.) A miniature
Some game masters find that playing with a map improves the game experience for all, and you're going to need to find a figure to represent your character on the tabletop. There are myriad miniature companies in the world, and i am certain that you will be able to find a figure that truly represents your character on the tabletop map.
If you aren't sure what kind of character you want to play, and aren't so certain about all this gaming stuff, you can find token collections or print and play options from a variety of retailers. If all else fails, you should be able to find some little green army men in either your toy box, or at the store.
b.) A calculator
Some games have a lot of math involved, and if you aren't math friendly (or math tolerant) this can be a problem. A calculator can simplify the math you're expected to calculate, and it keeps the game moving without everyone waiting for someone to do that calculations. Calculation heavy games are a lot simpler if you have something to help you with the math.
Now, i'm sure some of you are aware that your cell phone has a calculator on it, and it works most of the time for that purpose, but cell phones can be a distraction at a gaming table, and you may want to check with your group of players before whipping it out.