Should I sell out all ETH? Or keep ETH on hand and keep mining patiently in order to come across next bull trend?
If you mine and keep the ETH that you haved mined for a longer period than you not sell just because your ETH dropped a bit in price recently and i would just continue mining
When you are mining and instantly selling your mining rewards than you should check from time to time if there are other coins that are more profitable to mine at the moment with your equipment.
https://whattomine.com/ can be used for checking.