As a freelancer, a contract is the most important document to align with the client on an assignment and to protect yourself financially. You should not start any project until you receive a signed contract from your client.
This video will take you through the bare bones of what should be outlined in your contract but feel free to do further research to protect yourself even more.
Thanks!
Peter Barr September 18th, 2018, in the afternoon
I recommend using https://www.and.co/ which is a very handy free tool for all your freelance projects. It includes a built-in contract and proposal creator, with digital signatures, which very simply builds your contracts using The Freelancers Union's open source contract. I'm not affiliated, in case you are wondering, I just think it's great!