How to protect yourself from deception?

Question

Freelance

Good evening.
How can I protect my project.
If they throw it, what would I be able to control from my server over another site that I made. Delete code, close. How can you implement to be calm.

Answer 1

The other side has exactly the opposite interest.
The most practical: mutual insurance - the work is given in small pieces gradually, also gradually and paid.

Answer 2

To insure - only by running the site made on your hosting.

Answer 3

You must have key access, and give them a copy and after payment provide all passwords