This is the ultimate way to layer for the summer. Find a vest that you love, and add it to a comfortable longer tee (stripes are always good) over your favorite jeans or white pants. With long vests, I always make sure they are adding to my outfit without being too distracting. Look for neutral colors and lighter weight fabrics and you'll be good. When wearing hats in the summer, the key is looking put together with minimal effort so don't overthink your outfit too much or stress about perfect hair. Think casual. My hat is currently on sale under $20!
I'm so glad I got this lilac top. It's seriously so versatile, and the color is amazing. I wore it here with white pants and wedges, and look how perfectly it works tucked into a polka dot skirt. Solid tops are always a great investment for that reason; you can literally add them to any kind of look (especially patterns with the right color combos), and it turns something basic into a unique, tailored look.
Lace tops are perfect for summer. They easily dress up your outfit, and they are lightweight and airy. I linked to three that are really pretty and detailed (but all a little different). Because lace is naturally so feminine, adding a distressed pair of jeans gives your look a little more edge, which I like for nights that are more casual. You could just as easily add your favorite lace top to white pants and heels for a dressier look.