Nathan did a great post on that a couple of days ago.
Usual rules - copy ZEC key, move ZEC to new zaddr, wait for some blocks, import key to YEC wallet, wait for some blocks, move YEC to new address. I did mine with ZECwallet/YECwallet, all quite painless.
Edit:- Here’s a link to Nathans post :-
User considerations around chain-splits/airdrops including Ycash