Severance offer, what should I ask for?

I was offered 13 weeks of severance after 13 years as a social media manager, and I have a few days to sign. Any experience at all would help. I do not want to leave money on the table. Did anyone negotiate and succeed?

Read the release carefully. Mine included things I did not expect, like a non-compete.

Keep everything in writing and save the confirmation numbers. It saved me later.