Most of the freelance projects I take on involve working remotely, for a fixed price. I'll then take a deposit before starting work and invoice for the rest on completion.
However on occasion I find myself working at clients' offices for a day rate and I find billing a little more tricky.
In the event that there's any dispute over how many days work I've actually done, how do I prove it?
And would it be acceptable for me to invoice every week? As I feel most places expect an invoice once per month, but I dont like the idea of doing an entire month's work up front without having had any form of payment.