What are some good ways to add interest to a basic wardrobe when the weather is very hot?

When the weather is mild, I like to dress up my basic tees and jeans with short sleeve or 3/4-sleeve cardigans, denim jacket, scarves, etc. However, in the summer, it will be so hot on some days that even a scarf will be too uncomfortable.

I have been interested in statement necklaces, too, but I'm unsure what to look for. I mostly wear scoop neck or v-neck, as I'm a little busty.

I wear a lot of basic tees with jeans (boot cut, skinny, boyfriend, colored, etc.). I've also recently bought a cute black and white maxi skirt and a black knit a-line skirt (above the knee). I'd like to look fashionable while also staying comfortable. As most of my tees are solid colors, what should i do?