Several ways to get a 737 down, all depend on the speed you will be at. Speed brake doesn't do much unless you are fast. It is quite effective at VMO but the buffet is awful.
Fast, Gear down (known as the Boeing speed brake) and pull the speed brake handle.
If you are going to slow down, you have to get the flaps out because the maneuver speeds are high (due to rudder issues). 1 & 5 don't do anything much to get the airplane down but flaps 10 does. Have to stow the speedbrakes before flaps 10 as the aircraft really buffets with flaps 10 out. Flaps 10 the airplane comes down fairly well.
Flaps between 0 and 5 takes a long time. Very loooong time if you find yourself fast or high. Gear down will get the little fat airplane slowing down while the flaps come out.