for example, backup the wallets, anything else we need to do before and after the hard fork?
What hard fork?,
Overwinter is a hard fork: https://z.cash/upgrade/overwinter.html
@lyhistory if you are running a full node, a backup of the wallet.dat is a good idea but not 100% necessary. Be sure you are on 1.1.0 or later and keep the node running during the fork to help propagate the new rules.
cool, yes, I backed up everything, wallet and private key, I’ll keep the node running on my laptop overnight to give my support