[AndrewLiptak]

I write a lot of articles for a handful of sites, so in instances where I need to specifically invoice a project, I use Invoice Generator: https://invoice-generator.com/

Suuuuuuper simple, and it keeps track of the invoice number each time I download a new one. I just put in the right details, download it, and send it in.

To keep track of projects, I use Trello: I've got a bunch of columns that I have for "Approved" "In Progress" "Completed" "Invoiced" "Paid", which helps me remember where, what, when, and how much I need to send in. It's a little clunky, but I've got a good workflow with it.