Weigh up the pros and cons of the new client relationship
Make sure that you and your client are on the same page
Define the scope of your work and the price. Include all the terms agreed upon by both parties in a proposal and contract.
Inform the Client
Discuss your work process, how you'll deliver the project, how you'll collaborate with them, when will you consult them for feedback, etc.
Initiate regular communication
This will help avoid delays, keep the client on the same page, and ensure that the project is on schedule.