Painting Base Boards-need tips

I am not a painter by trade but for the past several days I've been helping a friend get his new-used home ready to move into.

The last hour of the day, I spent painting baseboards with a cut brush laying down. The floor is Terrazzo so I can scrap off any paint that I get on it.

What's the fastest way to paint them. Do I need to use a plastic guard or masking tape or something to protect the floor.