It's important to stay away from blacklisted districts. Don’t roam around late at night if it is not necessary. Don’t go out and drink irresponsibly: as all idiots know, drunk people are an easy target for crime, and don’t flash your money and expensive stuff around. Dress down if needed (I dressed appropriately like a hob
However, we managed to enjoy our days in this city and we didn't feel any 'fear atmosphere'.
First and foremost, NEVER hail a taxi directly from the street. That's what I was told from many of my Bogotan friends, so I downloaded an app for taxi called Tappsi. Easy to use, trustable, and you will get your taxi anywhere you are. This apps also works in most other big cities in Colombia. Seriously tho, this apps is ZE application you need to have when you are in Colombia. At first, we were thinking to take the Trans Milenio (Bogota bus system) to go around, but it is often too crowded and taxi fares are relatively cheap, so we opted to take a taxi wherever we went.
I really love the Tappsi app. It tells you your driver's name, your taxi door number, how far he is from your location, and the detailed summary of your trip (how much you have to pay, how many minutes you did to get to your destination, how many KM, etc). I honestly think this is the best and the safest way to get a taxi in Bogota (and some other big cities in Colombia). The drivers are also equipped with a GPS to help them along (and at the same time you can see if they are turning around for nothing). Their costumer service is also very responsive. I highly recommend this app.
All the taxis you order from Tappsi are guaranteed to have a meter machine, so you won't get a surprise fee charge at the end of your trip. There are however two types of meter machine, the one that shows you the exact fare, and the one that shows you the unit meter (what the heck is unit meter? check this link here to know more).
One day, we took a taxi that used unit meters. So at the end of the trip we asked how much do we need to pay and since none of us speak the same language, I gave him a pen and a paper to write down the amount but he gave me his phone number and autograph instead... ... ...
The pollution is so bad, it makes it hard to breath
Before blaming on the polution and air quality, check if it is the altitude sickness that actually gives you the breathing problem. Learn more about altitude sickness on this site here.
Money and prices are always very relative to what country you come from. From my North American point of view, the cost of most thing in Bogota were either much lower or equal to what I was getting back home. But I can see how the prices for a local might be high since the salaries are generally lower. Compared to all other cities we visited in Colombia, Bogota was the most expensive for common goods (food, beer, transport, etc).