First of all, welcome to the forums and to ACNL! New Leaf was my first animal crossing game, too ^~^ I've been playing it for two years now. So here's some general useful information...
1. You can create up to 4 characters. I would recommend doing this early on so you can pick the perfect spots for their houses. If you wait (like I did) then you might end up with villagers you love and don't want to give up in spots that you'd like to place a character.
2. You earn badges for in-game accomplishments like catching every kind of bug, fish and sea creature, playing for so many hours, doing so many favors for your villagers, writing so many letters, etc. The guy that gives them to you is named Phineas. He's a super cute sea lion c:
3. Villagers recommend public works projects (pwps) that you, as the mayor, can build in your town. They cost money to build, though. Villagers will slowly donate to the pwp, but it's much faster and easier to pay it off yourself. Some pwps are only suggested by villagers with a certain personality type, while others can be suggested by a villager with any personality type.
4. You can write letters to your villagers, and even send them presents (which they'll often put in their houses). You can send them furniture, clothes, and even music (as long as they have some form of music player in their house).
5. After paying off your first house loan (which gets you out of a tent and into an actual house), the old mayor, Tortimer, will appear. You talk to him on the dock on one of your beaches, and he tells you about a tropical island you can go to. You'll be able to visit it the next day. On the island, it's always summer, so you can catch species of bugs, fish and sea creatures that only appear in summer, and even a few island-exclusive species. You can also go on tours, which are like mini-games. Each tour gets you medals which you can spend on items available in the island shop. After you've earned so many medals (50, I think) you can become a club tortimer member and visit an online version of the island where people from around the world can join you. Up to 4 players can be on the island together.
6. There are different kinds of bridge pwps you can build in your town. You can have up to 3 bridges, but if you have all 3, then villagers won't suggest anymore bridge pwps. Keep in mind that you can build a pwp really close to an existing bridge, but you can't build a bridge really close to an existing pwp. Because of this weird rule, I highly recommend you wait until you have your ideal bridge pwp before you build permanent pwps like the cafe, campsite, windmill or police station. Once you build permanent pwps, you can't demolish them, so it's easy to create spots in your town where bridges can no longer be built (I hope that makes sense).
7. Your town has an environmental rating that helps determine how satisfied your villagers are with the town. If you have more than 10 items on the ground, your environmental rating will lower and Isabelle (the mayor's assistant) may tell you that your villagers feel like they're living on a landfill. Keep the ground free of items and weeds. Dig spots (which look like a little star on the ground) don't affect your town rating, and neither does fruit. Baskets of fruit (that you get from stacking fruit in your inventory), however, do lower your rating. To raise your town rating, plant lots of flowers, trees and shrubs, enact the beautiful town ordinance (which eliminates trash from appearing in your ponds, rivers and oceans, and makes weeds appear very rarely), and build pwps like the wind turbine and solar panel. Eventually you can have a Perfect Town rating, which unlocks the flower clock pwp, and (after 15 straight days of having a perfect town) you get the gold watering can, which waters up to 9 flowers at once, instead of one (normal watering can) or three (silver watering can).
That's all the info I have for now :3 Hope this helps you out.