Sure, ctrl(windows)/cmd(mac)+m and ctrl/cmd+e are go to’s, but here a very short list of some helpful extras:

ctrl/cmd+alt+shift+e – collapse visible layers to the selected layer while retaining the other layers

ctrl/cmd+shift+e – collapse layers

ctrl/cmd+e – collapse down a layer or collapse selected layers

ctrl/cmd+g group layers

ctrl/cmd+shift+f – fade filter after you use it ( I think I used this once, a very long time ago )

q – quick mask mode ( I’ve been asked why users can only draw red many a time )

ctrl/cmd+alt+shift+r – rasterize layer ( Custom shortcut that saves some time )

shift+g – cycles through sub tools