Abstain from drinking, eating, chewing gum, and smoking in public during daylight hours.
Be respectful of the way you dress. Ladies, cover from cleavage to knees, please. Not a bad idea for you guys, as well!
Curtail any road trips in the hour before sunset, due to hungry people driving in a mad rush to get home to prepare for their breaking of the fast or iftar meal. I know, driving crazier than usual, hard to imagine.
'Sup at one of the lavish Suhoor buffets at Doha's finest restaurants, such as The Ritz. The food and cultural experience is worth the pricey entry fee.
Also, don't forget the malls, government facilities, and retailers in general will have adjusted hours for the season. Restaurants, other than a few at hotels and very select venues, will be closed during daylight hours. Things, as a rule, don't run quite as smoothly during the season, so above all, keep your patience. Ramadan Mubarak!