This is an invoice template that I created for my personal use as a freelance musician. I saw someone was asking about using invoices as an SM some time back. I have never used it for my SM gigs because I rarely get to set my own rate...I just accept or reject what they offer. Nevertheless, I thought I would post it here in case it might be useful.
Totals are all set up to calculate automatically. I choose my base unit (hourly, weekly, etc.) and list that as the quanity, set the unit price, and it will calculate the total for each service plus the total for the project, minus any initial deposit.