What should I do before jailbreaking?

[duelingdragons]

I don't want to lose ANYTHING (songs, videos, contacts, pictures, etc etc...)

So should I just "sync" my phone before I jailbreak?
I know from what little research I've done that it will build me a custom IPSW file.. will that contain all my data?

Once its been jailbroken, can I just restore using that file?

Sorry, and I am going to go read all the FAQs now. =)

[ilfn143]

do backup, after j/b right click on your iphone in itunes then restore from backup. custom IPSW file is just a firmware file.