I do my best to blend in whenever I travel. I do research beforehand to find out what it will take to look like a local and do my best to follow along with what I've learned. Being conspicuous and looking like a local is something I like to do because I feel like it's respectful to the people of the city and I also do it for myself, as it helps me have a safer experience. Sticking out turns you into a target for thieves (and as a woman, I don't want to attract any other criminals, if you catch my drift) so I do my best to behave normally.
LOOK THE PART
Dress like a local. That doesn't mean you need to don a costume; you don't need a beret and breton top in France or a woven poncho in Peru. But, if you're heading to Italy, dress up a bit. If you're visiting a mosque in Istanbul, cover those shoulders and knees. And above all else, avoid graphic T's that declare your love for the city you're visiting and burn those fanny packs.
Carry a bag big enough to hold the cam or if you insist on keeping it around your neck (lest you miss a photo opp), try using a cuter strap and not the default, bulky, ugly one.
And obviously you can't do much about your skin color but make it a goal to blend in.
NAVIGATE LIKE A LOCAL
One sure way to stick out like a sore thumb is to look lost. Use a map app instead of a paper map (though a paper map is always a good backup to have) so that you're not struggling, trying to figure out how to refold your street map. Plan your route in advance (either in the morning at the hotel or anytime you pause, like for coffee or during a meal) so you're not standing on the street looking confused and awkward. Keep your eyes peeled for street signs and keep track of where you're going.
Don't faff about with your money. If you're in a foreign country using foreign currency, memorize what the bills and coins look like so you're not fiddling with wads of cash for every transaction and screaming to potential thieves that you're an easy target. Take only what you need for the day with you - pulling out a giant stack of bills is unwise - and stack your money in order (1's, 5's, 10's, 20's) to make it easier to pick out what you need.
Hop on Duolingo and learn some greetings like "please" and "thank you," and maybe a few more essential phrases. And don't be that person who thinks that increasing the volume of your voice somehow makes it easier to break the language barrier.
Do a little people watching, be observant, and basically follow along. If you're in a fast-paced city, keep your speed up. If you're in a laid back destination, relax and slow down. If everyone speaks loudly, speak up; conversely, if everyone controls their voices, control your own.
EAT LIKE A LOCAL
Instead of sticking to at home favorites, try venturing out of your comfort zone to eat a local specialty. This may be difficult for picky eaters (I'm not going to lie, I have a lot of disdain for picky eaters) but even if you're squeamish, you can at least make an effort to eat the local cuisine instead of hunting down a McDonald's every time you're hungry.
What better way to look like a local than to make friends with a local? This is definitely the best tip. You can learn more about the customs, where to get the best food, they can point you to the best bar, the best coffee, the best views of the city, etc. Basically, you'll get insider knowledge on your destination and experience it like no typical tourist will.
So have fun!