Private Institutes- The best private institute is the British Council, but they don't hire very often. You can find out when they are hiring here by going here. They pay 40k pesos/hour.
I worked at two institutes. One is called Study Agency, this is their website. They pay 30-33,000 (pretty high end for private institute work) pesos an hour, and the guy who runs the school, Cormac Ross, is a great guy. The problem is they don't sponsor work visas, though there are other schools you can go to for that, while still working at Study Agency.
The other school I worked at is called Focus on English, this is their site. They pay 16-26,000 pesos an hour, depending on how good the boss thinks you are. He's fair about it (I got 26), and seems to base it on the response of the students.
I know of two other schools, called Business English Training and Extreme English (Andrea Harries- email@example.com) which are good. Extreme is supposed to pay 50,000/hour.
The schools you should stay away from are the chains. They pay very poorly and work you like a dog. The only chain maybe worth working for is International House, though even there the pay isn't as good as the places I work.
Work Conditions at Institutes- You go to adults' offices to teach them. I taught at La Roche, Oracle and Baker Hughes. You don't get reimbursed for transport, though the buses get you around real cheaply if not at all comfortably. You can expect to be scheduled for 25-30 hours a week with a full time schedule. Students do cancel fairly often because they are busy. If you're lucky they won't do it far enough in advance and you still get paid. You'll get 1-5 students in a class.
You can also get privates here for 30-50,000/hr. For those you just have to meet enough Colombians to find one who wants privates, or meet foreigners who are giving up privates that you can take over.
International Schools- These are the best international schools in Bogota. I've worked for Colegio de Inglaterra since November 23rd, and it's a big upgrade from teaching adults. The pay is a lot better (I'm averaging a salary of over 4 million a month), plus they will pay for your apartment, your flights, and give you three months paid vacation. The conditions at the other international schools are supposed to be similar. Most international schools strongly prefer university certified teachers.