Use your wide brush for the flat wall surfaces. To rid the brush of excess paint, tap it lightly, do not draw the brush over the rim of the can. Light long strokes will provide the best finish. To cover all bristle marks, first brush up, then down, then across, then up and down once more. Work from the ceiling down.
Paint crossbars first, then frames and finally the sills.
With a Roller - Rollers are made of synthetic fibers or wool. Short pile rollers are for smooth surfaces. Deep or heavy pile rollers are for rougher uneven surfaces. An extension handle for your roller is a good investment if you intend to paint ceilings. Before you start, make certain that walls are free of soil and that all cracks are patched and fully dry.