I'm all about making my flights as smooth as humanly possible. I've started packing more like a minimalist, and I've slowly but surely discovered some airport hacks that have made my life a lot easier. I think the key to a perfect flight is having what you need all in one spot: in your carry-on. If you're checking a bag, you need to know what's important to bring on board the plane with you and what's OK to leave behind in the bag you're sending off into the literal hands of strangers and metaphorical hands of machines. Here's what you should always have in your carry-on bag when flying.