many switches and outlets have easy wire connectors for 14 gauge wire,
12 gauge probably wouldnt fit, of course you can always wrap the wire
around the screws but sometimes its helpful to use the back install
connectors where the screw holds the wire

the backstap connections are poor quality i dont recommend them

try a little piece of romex in your planned outlets and switches.

of course you can pay big bucks for 20 amp rated outlets

keep the light circuits seperate from the outlets and dont foget GFCIs