Setting up your account with Apple is not really as easy as you might think. The actual setting up is not a problem, in fact most people have multiple! The issue is that you have to think through how you ultimately want to USE the account.
Your iTunes account is what is tied to all your purchases. This is actually a critical thing to remember. Sure, you can “share” Apps or movies, but you then have to remember which account has which App to download and/or update (the latter being super annoying down the road). For our family, we have the kids share a “kids” iTunes account. That way if they buy an App or movie or music, it gets shared with all the kids. Nice. Some prefer to keep everyone separate and let them handle it on their own, that’s great too, I just prefer to not double/triple spend for the same item.
You can use your iTunes account as your iCloud account as well (and most should/do). The issue to consider is whether you want to share your device or not. If your kids are using an iPad and that iPad is tied to your iCloud account, your calendar, contacts, etc. will all be on their iPad.
Another iCloud feature that is super valuable for families is Find My Device. How many times do you have a kid come to you complaining, “I can’t find my device, do you know where it is?”. Daily. Hourly. If they have their device connected to their own iCloud account, you can log in to icloud.com and do a Find My Device look-up and don’t even need to bother you!