1.) Layers are your friend - The temperature is bound to fluctuate, and wearing a cute tank with a light cardigan will be the smartest solution. Take the sweater off when it gets warmer, and throw it back on when the breeze kicks in.
2.) Add in fall colors - Wearing cooler items, like a sundress or tank top in fall colors makes the change in season less abrupt.
3.) Lightweight sleeves - Long sleeves in a lightweight material will keep you warm enough without making you too hot. When it's time to really breakout the sweaters, the difference won't seem as drastic.
4.) Denim is your best accessory - Whether it's a denim jacket, denim shirt, or a great pair of jeans, the fabric is great for the transition into fall because it's not too heavy. Adding a denim piece to your favorite summer outfit is the perfect way to start incorporating fall.