Under the $hit happens clause, we give our long term regulars a grace period & a phone call.
Otherwise, after 30 days, we send them a notice saying we will file with the credit agencies for every thirty days the bill goes unpaid. After 90 days we send a notice of intent to lien (this is cheap and I got boilerplate mechanics liens online). In Florida, I just pay the court clerk to file the lien (about $25.00 in Palm Beach) and while we always have written agreements, the clerk never asks for them.
Hell, I filed two liens on a guy living in PA, one on his property here and the other in PA, on his property there. I was never bothered with a burden of proof.
90% of the time telling them we will file with the credit agencies produces a lot of noise and eventually a check, threat of a lien (if it goes that far) does the same... don't back down, just say "don't pay and find out". For lawn care, I haven't had to file but one time with credit reporting agencies and have filed one lien. Guy was broke, oh well.
On the irrigation side we have threatened on numerous occasions and have filed liens, particularly against HOA's run by the residents. It's been very successively in shaking loose money.
Threatening peoples credit really shakes a lot of them up. Even if our legal footing is shaky, the mess it causes in their personal or business finances is enough to get them to cough up.
The know they owe you the money. They just think just because we are lawn turds they can walk on us. Don't let them, you'll never do business with these guys again anyway.
It really pi$$es me off that they think they can just shaft me because I run a property maintenance business and presumed not smart enough to stand up to them.