As long as you do state and agree with the clients how many days Invoices should be paid by, Mine are 30 days, which I think is pretty much standard. I just point out this fact to any new client.
As for domestic non payers its the same standards really, when you took the job on, they employed you and you agreed terms (or should have done) pay when done ect via bacs, cheque or cash.
I have a small leaflet that I post thru their door when they owe more than twice, which simply states that their account is now in arrears, asking them to post their payments asap, if I dont hear from them, next time I go I put a similar one thru the door stating that we are now adding interest on, and will without further notice start legal proceedings if not paid within 7 days, usually works.
But I always door knock a few times first, Sat mornings are a great time to catch them in I find.
NEVER EVER let them get away with it! You do this for a living, these are your wages!
Good luck.
For ORI.....
here's the bottom text from my invoices....
ALL INVOICES MUST BE PAID WITHIN 30 DAYS OF ABOVE ‘INVOICE DATE’
We understand and will exercise our statutory right to interest and compensation for debt recovery costs under the late payment legislation if we are not paid according to agreed credit terms.