Bottle selection

Get the kind that filter out the air and bubbles (like Dr. Brown's or Ventair). It keeps the baby from swallowing the air which will reduce spitting up, gas and keeps the nipple from collapsing (so the baby won’t have to stop and start again throughout his feeding).
I think the Ventair are probably the best because they have a disposable liner bag (if I'm thinking of the right ones). That way you can just wash the nipples and you’re ready to go again, without having to constantly wash bottles. Trust me, it’s a pain. I got the Dr. Brown’s, which work great for filtering out the air, but are a pain in the rump to clean.
**Even if you are breastfeeding, you should still be sure to have some formula and clean bottles ready to go. You never know what the day might bring.