Microservice should be designed around the service they provide in the system.
So for example you might have a user service that's sole responsibility to is to store and authenticate users. All other services in your system then use this service to authenticate users.
And you might have a document storage service, that does nothing other than store a document (ie it doesn't also worry about user authentication, or converting the document to different formats per request)
I'm not quite sure what you mean by "model the services around operations", but if you mean you have a microservice for
GET and a microservice for
PUT, and each microservice has all the services to handled this task inside it, then no that would not be a good idea and sort of defeat the point