Do I still have any friends here who are not well-to-do? Perhaps with some consumer debt that is in default? Who might, once in awhile, hear from a debt collector? Well, this is a topic that interests me, partly because I had a go with this problem several years ago. I beat it because I had a lawyer friend who told me a couple of key things that are strongly confirmed by this article, which has a few things that were not pertinent to me back then.
1) Do not ghost the collector. The main way they get you is by waiting 30 days and then seeking a default judgement. This judgement will be legally binding and allow them to take your money against your will.
2) Do not talk to the person. Tell them to send you a letter, give them your address (I know, scary but the right thing to do). DO NOT TALK TO THEM. No discussion. No "I can't afford it right now." Get their details, name, mailing address, case number (make sure to confirm the hell out of the case number and that it is the correct reference; these people are liars).
3) Send a registered letter well with 30 days of hearing from one. Dispute the charges and ask for documentation in the form of a signed contract. (Other ideas are in the article.)
4) If you always show up on time and say, "Show me the contract", you will beat them.