Each time characters level up, ask players to describe their characters' new abilities. One way to make our games great is to regularly talk to our players. I've written before about the value of talk...
Ask players to describe everything, but not all the time. There will be key moments and as a GM you start to develop an intuition for when to ask "what does it look like when Hector the Well-Endowed casts Eldritch Blast?"