You are very tall here. You'll get attention (not so much in tourist/rich areas). Downtown is always overcrowded, but it's also very well protected by cops in each corner. The only risk you run in downtown is being pick-pocketed (just keep your things in your pockets and don't use big backpacks or put your wallet on the back pocket).
Try to use only taxis painted with white/pink, they are the newest and verified by law. Fake taxis are uncommon, but you are better by just using uber (make sure you got data roaming on your phone all the time), very few taxis may try to overcharge you as soon as they see you are a foreigner. Dangerous taxis are mostly on shitty urban suburb zones, and are uncommon, but as long as you stay in the good part of the city, you'll be alright.
If you are a woman and wear tight clothes, you'll get attention from almost every piggie man. Just use normal jeans, the weather is varied, suddenly it can start to rain or get very cold.
You can carry expensive gadgets, but dont use them in middle of a crowd, pickpockets always try to spot distracted people. Stick to downtown, bellas artes, reforma, tourist zones, and areas where you see a higher life quality level and where the people and the place are good-looking (white or not so dark skin, fine clothing, suits, nice cars, clean streets, nice buildings, etc) and you'll be very safe and fine.
Downtown is tricky, it can take you from a safe and touristy/historical area, to a shitty/dangerous one before you notice it. Avoid getting in crowded market-streets like in pic related, there's no historical attraction at all in those places, and you'll get insta-spotted by thieves. Mass cheap clothing stores and dark-skinned guys with shitty gang-looking and caps and tattos are red flags, avoid that kind of places.