As I live with multiple extroverts and have befriended a few, I've learned a few things. If any extroverts want to correct me or add anything, I will be eternally grateful. And just like with my last post, everybody's different, and not all of these things are true for everybody.
That being said, let's get on to a few things to remember when writing (or just generally interacting with) your extroverted people. Because let's be fair, they need taken care of and are kind of your pets.
1. Extroverts get their energy from other people, and like to make friends.
Just like how introverts get their energy from solitude, extroverts need to be around people to charge up. This doesn't mean they don't appreciate peace and quiet, they might even relish it, but eventually they have to resurface for some human interaction. Make sure they get this as often as food and water, and be sure to let them socialize with other extroverts on their daily walks.
2. They can be impulsive or randomly decide things.
Of course this can be true of some introverts, and this isn't true for all extroverts, but I've found that as a general rule, extroverts are more willing to dive headfirst into things. You may need to occasionally hold them back by their sweatshirt hood and give them a little talk about responsibility and waiting until everything's been thought through.
3. They can be very open about how they feel.
If you have a feely extrovert, they're probably not going to hide it as much as you might. They're going to want someone there to talk about their feelings and have a shoulder to cry on or an ear to squeal into deafness. These moments are best with tea and your extrovert's favorite blanket, and can be improved by promising them a social event the next day. Feeling type extroverts aren't shy about their emotions and often process them externally, talking through their problems instead of hiding for a while to sort them out alone. Always have other extroverts available in case you need backup for an emotional breakdown, and find someone to take care of yours for a day or so afterwards while you process the emotions they've given you.
4. They can talk without thinking.
Most introverts like to think about what we're about to say before we say it. Extroverts don't do that as easily, so you have to remember that what your introvert says might just be a random thought that popped into their head. Sometimes this can be mean, or hurt your feelings, but they might not realize that. Be patient with your extrovert and remind them that it's best to think about what they say and the consequences it might have.
So there you have it! Some ways to keep your extroverted characters happy and healthy. Keep in mind that they're not all the same, but they all need a good introvert to take care of them and keep them from doing anything silly like buying all the chocolate in the store, shutting themselves up for too long, or spilling their emotions to the obliging lamppost. Have fun writing them, and don't be afraid to ask them for advice if you're not sure how they work.
*And please remember that I myself am not an extrovert, so I might not be right about everything. If there's anything you'd like to add, feel free to use the comment section.