A few points the usual manuals don't cover:

Get over yourself. Even if the macho guys you hang with laugh at you wear a long sleeve shirt, a wide brimmed hat, and sunscreen. Do not try to tough it out. Take care of yourself even if those around you don't.

Slow down, pace yourself, take frequent breaks, in the shade if at all possible. Reschedule physical labor to get the jobs done in the morning and evening. Schedule the work so the location is in the shade. Sleep, rest, relax in the heat of the day if possible.

Some people will feel washed out if they sweat a lot, no matter how much water they take in and after they have cooled off, and they need salt. Most people, in most situation, don't need extra salt. But some do. Know yourself.