Never paint color immediately from the paint can. The paint can contains dirt which your brush can pick and hamper your walls. The specks can change the shade of the wall causing damage to your painting.
Opened paint can bring dryness to the paint due to exposing in the open atmosphere. The exposure of the paint to the atmosphere will make it sticker and thicker. Carrying the paint hitter and titter will be a cumbersome and bulky job while painting. The paint which should be enough for that particular wall must be poured in the bucket which will be easy for carrying.
Storage of paint must always be done in paint can only which will not be wasted. Small amount which is poured from can to small mug can be used faster and drying will be less. Painting thin coats will help the paint spread better which will give a good finishing. Cover the bucket or mug which the paint is poured which will avoid exposure to air. The roller which is used must be soft and painting will be easy depending on the area.
And selecting a good color paint based on the room conditions would do a lot of good to the users.