My best piece of advice is to keep an optimistic mindset and focus on the joy these two new lives will bring to your family. Yes, it's challenging - especially in the first few years - but there's so much magic too!
Organize and simplify your life as much as you can in advance of their arrival. Stock your freezer with meals. Set up a system for keeping track of feeds, nappy changes and sleep, at least initially - it helps you learn their patterns quicker and gives you some data to share with the pediatrician if needed. Accept help when friends and family offer it; no one can do everything themselves!
And remember, there's plenty of joy in having two: watching them play together, seeing them comfort each other, and knowing they have a lifelong mate - these are special things that make multiples so wonderful. Congratulations and good luck!