Opinions run the gamut on this one. Some moms swear by their large, multi-pocketed diaper bags, while others simply stick the bare necessities in a favorite tote and are on their way. No matter what route you go, remember the golden rule: the bigger the bag is, the more you’ll find to fill it with.
Look for a long, adjustable strap. Being able to wear the bag over your shoulder will keep it from slipping off your arm, and the adjustability factor is key if you plan on sharing the bag with a partner or caretaker.
This is more of a necessity if you'll be out in an urban environment. Short straps (or an adjusted long strap) can also do the trick, though. If your stroller has a large enough basket, you might not need to worry about this aspect at all.
While these come with many diaper bags, they're not always large enough to be useful — especially as baby grows. Check on the size before you buy if you're keen on this feature, or be prepared to pack a pad or blanket of your own if the included one isn’t big enough.
Lots of outer pockets make it quick and easy to find whatever you need without rustling through a seemingly bottomless bag as baby fusses. You can also designate certain pockets for your own essentials, like keys, cell phone, and wallet.
Look for a bag that stands up on its own — this makes it easier to reach in and find what you need with one hand. (Making the most of every hand you've got is crucial when dealing with a squirming infant.)
If you plan to share the bag, look for a color or design that all parties will enjoy (or at least tolerate) wearing. Sharing the bag cuts down on both cost and time — no need to transfer items from one tote to another.
Consider your needs — if you cloth diaper, you'll need to carry more accessories. And again, remember the rule: If there's extra room, you'll find a way to fill it.
Look for solid closure (zippers are great) so that everything stays inside when you bend over or inevitably drop the bag. Stay away from Velcro, which tends to get stuck on things and can also wake a mercifully sleeping baby with the noise it makes when opening.
Other nice features:
Wipe carrying case Some bags come with these, but if yours doesn't, you can always purchase a travel case or simply use a plastic sandwich bag.
Inner tethered accessory bag
This still allows for easy access, but provides a little more security.
These are good for breastmilk and formula, but you can also get by with warm or cool packs.