Should I negotiate my severance? - what worked for you?

I was offered 8 weeks of severance after 8 years as an electrician's helper, and I have a few days to sign. There are 8 people counting on me, so I am trying to be careful. There is a non-disparagement clause. What did you ask for?

I asked for two more weeks and a neutral reference. They agreed to the reference and added a week.