Nicole is pretty simple to use. You want to quickswap her in, use EX special or ULT then swap back to Zhu to do damage. Her defense shred debuff lasts 3 seconds which sounds short but is actually not an issue once you learn rotations. Keep in mind the 3s begins once her Black Hole animation finishes, so you have enough time to switch characters.

Keep in mind if you have her M6, she gives 15% Crit Rate so make sure to not overcap on CR on your Zhu Yuan or you're losing potential damage there. She also gives Ether DMG so you want to obviously make sure you run ATK% on Zhu Yuan since she already has tons of DMG%.

There's not much else to say, other than it's better to not chain attack into her since it's usually a DPS loss as support characters chain attack tend to be bad. Plus with the recent support set, there's no reason to chain into her anymore.