For fabrics, I would suggest linen, cotton and lightweight wool. Silk is also good, although not as cool as linen.
If you have a RL outlet by you, you should be able to find linen pants and seersucker suits on the cheap. I have several pairs of linen pants from various companies, used to have a linen sport coat though it is now too large to wear.
Of course a seersucker suit, preferably three piece, is a necessity...Light colored or neutral linen fabric, and madras is also a vintage fabric that is big now. I own a pair of madras pants that I pair with a poplin khaki jacket, or a double breasted blazer. Good stuff, good stuff...
