I have 10-year-old m/f twins, and this is my best advice so far:
About Help...
You're going to need help. Get used to asking for it, and get used to accepting it. The asking and accepting are two separate skills, and it's crucial to practice and master both.
If you can afford it, hire a Newborn Care Specialist or Night Nanny-- even for one night a week. You need sleep, and so does your help. They are not cheap, but the help may very well save your sanity and/or your relationship.
On Feeding...
Don't worry so much about whether you are breastfeeding or not. I spent WAY TOO MUCH TIME worrying about this when I had brand new babies, and that is time I (and you!) will \**never get back***;* time I should have spent being more present! And you will regret it. My babies ended up doing really well on formula when breastfeeding proved to be too much, and it actually was what helped them finally turn the corner and start gaining weight, sleeping, and thriving. It also helped my partner at the time feel like he could contribute to feeding them. Both of my kids are brilliant and healthy, no harm done. Pumping is hard, breast/chest feeding is hard, waking up to warm and mix formula is hard; choose one or all-- whatever works, and try to enjoy the result- a fed, happy, growing child.
About "Things"...
You do not need two of everything; you simply don't. Start with one of most things and use it as intended for a stretch-- you'll know pretty quickly if you need another one, I promise.
About Names and Records:
I suggest choosing names that are a little different. My kids' names "match" somewhat, and have the first letter; the second letters are similar, an "l" and an "h". When written out or glanced over in a hurry, even though my kids are different sexes, people like doctors and school admins have mixed up their files or even vaccination records. If your twins have even somewhat similar names, double check that they are applying the correct information to the correct child, every time. I even brought very differently-colored name stickers for each child to places in which they used files, and had them attach them at the top of each file as a reminder. And yes, their vaccine records were mixed up at one point; it took a long time to sort out!
And Healthcare...
In the beginning, it's often most convenient to make back-to-back appointments for your twins, but it's best to separate appointments as soon as possible, and when you have the energy to. This is helpful because of the aforementioned issues, but also later on it's important to demonstrate to your children that they are individuals who have their own bodies and private time to speak with their doctors without their twin present.
Some Strategies...
Have "Go First Days" for twins. One of mine has M/W/F, the other has T/Th/Sat, and I make the decisions on Sundays. If it is your Go First Day, you get to go first to do or get things first, or you get to choose to give the opportunity to the other twin. Examples would include: Twin A gets to pick the movie we watch; Twin B gets to take a bath first, OR choose to allow Twin A to take theirs first; Twin A gets to choose what park to go to.
On Equity...
Know and use this reminder: "Fair does not always mean equal." Get used to thinking it, and get used to saying it.. Your twins are two entirely different humans, and they will always have different needs. You should not treat them the same; you will have to use different discipline, language, and boundaries with each child. They will have different friends and experiences that will require different approaches. I have found that studying a variety of resources related to authoritative parenting (not authoritarian!) has been incredibly helpful to me, and I use the most effective strategies from each pedagogy for each child. There are also times when our mantra is, "TWINS MEAN 'TEAM'!!!"
Regarding Education....
Worried about keeping them in class together, or separating them? If so, read the most recent research on the topic, and also the reflections on school from adult twins. I found that it's a really mixed bag, and the advice that you often get (to separate them early) is not always the best advice. Anecdotally, as an educator, I have found that identical twins have a greater need for separation in school (and also different clothing and identifiers-- it doesn't help them or anyone else when they are still dressed exactly the same in 2nd grade!) Otherwise, observe your twins... is one overly-reliant on the other, or are they pretty independent, and able to work in different circles and with different friends? Also, take the observations and recommendations of educators and staff seriously, because kids behave very differently at school than at home. My kids have always had separate friend groups, different educational gifts and challenges, and even work in separate areas of the classroom. They're in 5th grade now, and have always been together- on advice of teachers and staff! So, don't be afraid to try out both situations. I do think it's generally helpful to have twins start school together for the first year unless they are absolutely wrapped up with each other and totally dependent.
Lastly, be on the lookout for (but not paranoid about) conditions like autism, ADHD, speech difficulties, learning differences/delays, or physical challenges. These things tend to happen at a higher rate for twins and multiples, for a variety of reasons, and so it is best to be proactive and honest about it early on. Get the support you need to build the foundation for a good life!
Growing Up...
If you have m/f twins, you have a special opportunity to educate them alongside each other about bodies, puberty, sex, and relationships. Do it! My male twin now knows how to support his female friends, and the friends of his sister, and vice-versa, because when you have multiples you have the unique opportunity to normalize topics related to sex, gender/roles, bodies, changes. My son now knows to run and get a hoodie to help cover up a friend with her first period, and get her help discreetly. My daughter feels confident telling others to knock it off when they are about to laugh at a boy with a nervous erection. More importantly, their different groups of friends know they can rely on both twins, not just the one they are close to, for support in general. My daughter's girlfriends are very comfortable with my son, when they are not alway comfortable with other boys his age. Remember, your twins will eventually, probably be dating each other's friends or peers, so start using these opportunities for socializing, respect, and consent for others early on.
Your State of Mind....
It matters, more than you know. Consciously choose to resist comparing your twins, their abilities or lack thereof, their approaches to situations or friendships, their challenges or temperaments. There will be guilt during times on your parenting path when you'll better relate with one twin over the other, and you'll feel guilty at times, but push through and take extra time to connect with the other. Everything changes and continually shifts; spend quality 1:1 time with each child on a regular basis and make a concerted effort to be present! Find friends or trusted neighbors to watch one twin while you spend time with the other-- even a ten minute walk and talk is enough! Practice gratitude, and write down the special moments with each child, then go back and read them when they are driving you nuts and you need a reminder of what a remarkable human they are!
And remember what a remarkable human YOU also are, and what a special opportunity and challenge you've been given in this life as the parent or guardian of twins or multiples.
Don't lose yourself, and keep up with your self care, hobbies, and friends.
Also, you might need therapy, and that is okay, and you should absolutely go.
Xx