Start by holding R and moving your view down. When Samus nears or reaches the point where she stops looking down, let go of R and immediately hold L to lock the view at that point. Now run to the edge of the surface and jump off when you reach it, letting go of L at the same time. Then right before you reach the peak, use your second jump and simultaneously turn Samus left or right with the stick, never stopping until you land at your destination.

There are many other kinds of space jump techniques and slight variations of the l-lock space jump. Experienced players tend to use several variations and know which work best in different kinds of situations. The above method is the original, but it's not at all the only efficient way to do a good space jump; you don't always have to turn to make a jump, and you don't always have to look down and lock the view first.

One variation is to simply run to the edge of the surface you're standing on and tap L at the same time you jump off, then do the second jump and turning part the same way.