Hair ties: there's never a time that I don't 1. need a hair tie and 2. have a hair tie! No matter how many I buy, I always am loosing them or they snap super easily (with my thick, curly hair I'm not surprised!) I take at least three with me where ever I go and the no-show elastics that come in SO many colors are super fun! My black and white striped one is my favorite and it's perfect for when you don't want a crease in your hair when you take it back down. These have been a must have for me and I pick up a new pack whenever and where ever I see them. I also always have a couple of bobby pins with me because they're good for so much more than just keeping your hair in place!
Lipstick/lip gloss: if there's any makeup that fades the most often, it's lipstick! I always carry around the color I'm wearing that day for easy re application. My favorite and most used lately is YSL #7. I usually carry around a makeup bag but that obviously wouldn't fit in a small cross body so I just take the essentials.
Re-wetting eye drops: if you wear contacts like I do, you know how important these are! I recently switched to daily lenses (which I am loving and recommend 100% over the two weekers!) and my eyes get SO dry that I use these drops probably twice a day! The bottle is super tiny which makes it perfect and easy to carry around in a cross body - thank god!
Roller ball perfume: most perfumes come in roller ball form or at least a smaller bottle. I always look for these when I buy a new perfume so that I can carry it around with me to re apply throughout the day.
Card/ID case: another beauty of using a cross body is not having to carry around a 5 pound wallet with tons of change in the zipper compartment! Card cases come in so many different colors, brands and styles and they fit super easily in a cross body bag. I love my Kate Spade card case that I scored at the outlet a few weeks ago! They're easy to find and trust me you'll be glad you have one!
Chapstick: my two favorite chapsticks are Burt's Bees and Vaseline's Lip Therapy. Both are so hydrating and again, so tiny and easy to carry around! Next to my phone, chapstick is one thing I can never leave the house without.