Material: You should only wear summer friendly materials clothing. Linen and Cotton clothing is my best recommendations. They are airy, light, sweat friendly and comfortable.
Unsaturated: unsaturated colors is preferred during summer, these colors are on the dull side or lighter side.
These colors are preferable because they absorb less heat.
Tees: Try to wear Tees more often during summer. Make sure to buy summer friendly material tees. Worried about tanning? Go for full sleeves tees(example: https://extended-alpha.com/products/breathable-long-sleeve-shirt)
Shirt: Do you love shirts? Who doesn't.
Make sure to try half sleeves shirts this summer season. Simple patterns, stripes will look good too.