Go early (but not at night!). Do not walk between 12H and 14H solar hours (H-2 was in Spain)
Protect your head with a cloth dampened the effect the fridge cool and put on sunscreen.
Take off your shoes very often, refresh your feet and don’t foget to dry them very well!
Think to drink regularly (at least every quarter of an hour) starting from the first quarter of an hour.
If you are sweating a lot, so you will lose a lot of minerals and risk of muscle and tendon problems. Drink water rich in sodium, eat fruits and vegetables and possibly taking supplements or pills drinks, ask your pharmacist for advice.