- Negotiate for a half upfront payment and start only when you have received it. It will help you avoid clients that don't have the necessary budget and will save you a lot of pain.
- Document decisions done over the phone or in f2f meetings (e.g. send an email saying something like. As we discussed, we decided to ...). It will help you with unforeseen change requests that the client sees within the scope of the work.
If you are able to stand through the (subjectively) most obnoxious host in the history of TV shows, then you might like http://www.imdb.com/title/tt7804132/ this.
I absolutely agree. This is usually a first sign for me to back away from a conversation when someone I just met "blindly" defends or rants about a technology without laying a valid argument.