Change your appearance and get new clothes
First thing's first, and that's that whatever character you pick, once you choose their gender, you're stuck with it. You can't change their gender, at least at this point in time, although there's a chance that Nintendo might add that feature later. If you want a character of a different gender, you'll have to start over with a new character.
Changing the clothes is pretty easy. You start the game off with a number of different types of clothing. You can go to your items, then go to My Clothes, and you will be able to select anything else that you have in your bag. You can also use the tabs to look at clothing by its type instead of viewing all of it at once.
You can use essence to buy new types of clothing. The main place to earn new clothing is in the marketplace, which can be accessed from the map after you're done with the tutorial. Go to the marketplace and check to see what clothing is there, and then go there every time it refreshes to look for different clothing. You can also check the market boxes of any of your friends, or of random people that you come across.
To change your appearance beyond just your clothes, first, head to the "more" tab. Then go to the settings, which is the wrench icon. You'll see a bunch of options for your eye color, your hairstyle, and the shape of your eyes. The available options are based on the gender that you pick for your character.
Later on, the option to craft new clothes will be added to the game. As of the time of this writing, it has not yet been added by the developer; clicking on the Craft Clothing button will reveal a "coming soon" message. Finally, new clothes can be won via My Nintendo Rewards, and more are bound to be added as time goes on; Nintendo doesn't abandon their mobile games.
Various Gameplay Tips
Tip 1: In the early days of the game's release, you have all kinds of connection errors popping up. The most likely reason for these is that the servers are so full that you're simply getting errored out of the game, so your best bet is to restart and see if it works when you load it again. If you downloaded the game early on an Android off an unofficial site, save your game data, delete the game, and then reinstall it from Google Play and it will work properly.
Tip 2: Your main goal early on is to bring as many animals to your campsite as you can. This will require you to build friendship via talking and gifts (any red option in the conversation menu with said animal) and then have the items that they like in order to get them to come over. Once they're over, you can engage in all kinds of conversation and side quests with them. After you have 9 animals, you'll need to swap out one animal in order to invite a new animal in, as you can only hold eight at a time in your camp.
Tip 3: Once you run your map out of animals, hit the contact list to see who you can invite next, and then hit the map button from the specific contact's list and go to their camp to talk to them. Or, when you eventually run out of animals, while you're waiting for another game update, start looking for other players who pop up randomly in campgrounds and add them as friends, give them kudos, and scour their campgrounds for fish, fruit, shellfish, bugs, and other crafting items.
Tip 4: Once you expand your camper at OK Motors, you'll run up a loan with them, that you can then pay off in bells. The loan is on your term, though, and there is (currently) no penalty for going delinquent on your loan; you'll just have to get the loan paid off before you can do another expansion.
Tip 5: Once you run out of animals to unlock, your next focus (aside from simply working on the design of your area) will be to level up their friendship. Get the friendship up to level 10 and you'll earn double the materials for completing one of their quests; at level 15, you'll earn triple the materials for completing one of their quests. Once you have an animal's tier 2 amenity (unlocked at level 10) placed in your camp, they will be able to level up to 15.
Change your appearance and get...