A: If you work in a super-air-conditioned office, keep a cardigan or shawl in a desk drawer (or stash a linen jacket if you've got a closet), or tuck a cover-up into your purse or glove compartment (scarves that fold up small are good).
People in India deal with their muggy climate by dressing in layers, and so should we: Thin, loosely fitting pieces allow air to circulate and can be peeled off when necessary. This summer's delicate fabrics and unconstricted shapes make it easy; try doubled-up tissue tees, or a tunic over pants. Mix different shades of pale colors such as white or beige—they reflect the heat, while darker tones absorb it.
In this weather, I'm a fan of living, breathing, natural fibers. Synthetics, while miraculous for many purposes, won't keep you cool.