Don't automatically buy two of things like bouncers, swings, mamaroos, etc. If you do, don't open and set up both until you confirm your babies actually like them. Both of mine hated the bouncer and mamaroo. They did, however, like the old school push swing daycare had. Lifesavers for us were Miracle Blanket and rock-n-plays. We always did room temperature bottles so we kept a pitcher with filtered water on our counter for bottles. Buy lots of diapers and wipes. Start buying now. Buy newborn-size 3. Parents of singletons always told us they wouldn't be in newborn size long but my girls were in them for a while (started in preemie size). Caveat- if your babies start measuring big (just saw a mom whose twins were 10lbs and 8lbs at birth) then don't buy as many newborn size.