I believe in walking softly but carrying a big stick. I don't like to waste time because time is money in investing.
A strategy I've used is to take about $1,000 to $1,500 in crisp $100 bills when I go to meet the occupants. If the occupants are undesirable, I'll certainly have a friend with me. Let them know you wish to help them ease their burden and always ask them first what you can do to help them move on. If they say they need money, ask them how much it would take to help them out and how soon they could be out and leave the place "broom swept clean." If they are cash strapped (and they certainly will be), you can show them you have money in your pocket waiting for them if they'll comply.
If they say they aren't leaving, explain that you will work with them by way of cash if they decide to play by the rules (and show them the cash). If they don't play by the rules, the cash they're seeing will simply to to an attorney to have them removed forcibly, if necessary.