The holidays in my AD&D game are taken from the Grumpy Cat calendar in my kitchen. Stick out your tongue Day is a day of armistice when enemies can be thwarted by sticking out your tongue in an irreverent manner. Disrespecting this truce by then attacking angers the gods, and a random celestial or infernal creature appears. The orc my players' characters captured two sessions ago has revealed that his tribe plans to attack an elven town this Saturday. If you don't know what orcs are, you are in an excellent place to learn to play D & D!
This is not the game you walked by one day where people were jabbering about their characters buying magic items or having a lot of spells. In AD&D, you play a guy with a sword. Or a person with a metal pipe (mace) who knows some helpful prayers, or somebody just barely able to hold a knife who can cast one not-very-powerful spell. This was the acme of roleplaying in 1980, and the different classes of characters are balanced by having them advance at different not-very-fast rates, and being able to hire cannon fodder. That's right, you have troops. You can hire them at first level, if you get the money together. The monsters are tough and come in big bunches, and in this game you fund your advancement by getting a lot of muscle together. You don't have to be a man to play, and you don't have to play a man, but this game takes place in a sexist scenario. Women are barmaids and wives and occasionally merchants, and people will be talking behind your Joan of Arc's back. To put it delicately, human men are bigger and stronger than all the other characters, even half-orcs. AD&D was designed by wargamers who wanted their characters to be able to win wrestling matches. There are elaborate rules for that, and also for playing a Shaolin monk. Dex-based characters are hard in this edition, though. If you don't roll high stats, you might want to play a demihuman. Their jack-of-all-trades natures make them very useful, whether sniffing out secret doors or warning the party of a treacherous deadfall. Halflings (hobbits) are arguably the best fighters, if somebody doesn't pick them up and throw them off the battlefield!
The orcs think they can take the elves by surprise before they stick out their tongues. I'm not going to tell you what to do, but it's going to be a chaotic mess. I didn't mention some types of characters before: you might have heard other DMs' players berating a thief character for stealing from the party. That's good roleplaying, but the thief is probably the most important member of the party, and needs that extra treasure. Everybody gets to be good at something in AD&D, and besides sneaking up behind enemies, you need your thief to look for traps at every turn. They are inevitably going to get poisoned or blown up opening a chest full of treasure, most of which does go to the rest of the party, and you might as well let them have a good time and get as powerful as possible to help the party before their player has to roll up a new character.
Thieves are the lowest class in society, and take a lot of abuse if their profession is revealed publicly. Fighters are at the top, but they don't always have the Charisma to take charge. If there isn't a paladin or ranger in the party, a cleric or magic-user may be considered the leader. This doesn't mean that player calls all the shots; however, if people are dithering in combat or do dumb things that keep other players from being effective, I may appoint a sensible person to be in charge of combat. Gary Gygax uses the word "obedience" as an indicator of how fast a player's character should be allowed to advance!
Being dumb can add up to three weeks to how long it takes to train for a new level. It also costs more. That doozy you heard about characters carrying doors out of a dungeon to sell didn't come from people playing the Rules As Written. Dungeons are full of treasure, so much that you always have to leave piles of copper behind. To get the best hauls, though, you have to stalk the tribes. Orcs, kobolds and other monsters always have lairs, not infrequently containing magical treasures. I will tax players 3 gold and 7 silver pieces a day per their experience level. That's 10 gold every 3 days, or 100 a level a month, only while you're in civilized areas. Why? Did you ever read how much a meal or staying in an inn cost in a book? If somebody haggles it's off to the side of the story to illustrate their unbecoming personality. When you have the money I tell you how much you're spending carousing and buying things you don't want to keep track of, like candles and arrows. (Lantern oil is an exception: it costs a gold piece, weighs a pound in the typical container, and you can throw it like a Molotov cocktail.) The basic men-at-arms you can start with are a bargain, costing you 2 1/2 or 3 1/2 silver pieces every 3 days depending on training. You have to buy them armor and at least one weapon, though! I run by the common convention that you receive experience for killing monsters, and by the gold piece when you acquire portable wealth or sell other items.
Probably the most important expense in AD&D is tithing. It doesn't have to be 10% unless you're a cleric or paladin, but pick a temple because you want them to like you when you show up wounded! AD&D is an exercise in realism, as though books, scrolls and other items had really been magical back in the Dark Ages. Natural healing is slow, there are diseases, and it might even rain if I remember to roll for it. This is a challenging game: people's characters die occasionally, and always be ready to run because random encounters are not going to be level-appropriate.