Make sure you and the people you ride with are clear on the signs of various sorts of heat stress and that you all know the first aid needed. You can go straight from "fine" to "heat stroke" without passing through any of the milder forms of heat stress.

Bandanna under your helmet. Get it and your hair wet *before* you ride. A neck cooler can also help.

Most people do not need a lot of electrolyte replacement, and shifting to more plain water may help. It takes energy for your body to get rid of excess electrolytes, so too much is not good. It's a lot more common to overdo needlessly on electrolyte replacement than it is to end up truly short. Talk to a doctor about this one. People's bodies are different. I really *do* need to overdo a bit on electrolytes (or I start refusing them because they taste bad) and I do better with alternating plain water and an electrolyte drink. Even for me tho, the classic "pee clear" advice is pretty much true.

Wearing loose layers can feel cooler than skintight clothing. Sometimes more skin coverage can feel cooler than being as bare as possible. Lighter colors can feel better than darker ones. Experiment a bit to see what works best for you.

Your hands and feet are your body's best radiators. Shoes, socks and gloves that breathe well and allow access to the big veins are a Good Thing. You can use frozen water bottles at the big veins to get some serious cooling going.