What are some parts of your agreements you consider non-negotiable? Or something you decided to add because you learnt the hard way?

I recently did some freelance work and due to a misunderstanding of what would actually be delivered, I decided to draft up a short but written agreement for future clients.

Although a written discussion was had about what was to be done, it appears both parties had different ideas about what would happen.

Im largely dealing with a client I get on well with and wanted to keep things simple and the template I've got is:-

Event name:

Event dates:

Overview of services to be be provided onsite:

Specific services (if any) : (shots considered essential)

Dependencies:

Deliverables: (quantity, format , delivery timeline)

Copyright: (stay with photographer or rights to be signed over)

Post event services: (any editing that may take significant time)

Cost and payment schedule: (booking fee, payment milestones)

Limitation of Liability: under no circumstances shall I be considered liable for more than the agreed cost of services to be provided.

Travel arrangements: (these might be omitted from what is sent to the client but should be considered)

Accommodation:

Food / Incidentals:

Is there anything you would add ?

Edit: if it was something I'd consider for use with the general public then I would go through a lot more rigour and probably involve lawyers.