The easiest and safest way to position a tall ladder against a wall is to push the base against the wall, walk the top of the ladder up until it’s vertical, and then pull out the base.
The angle at which the ladder is placed is critical to safety. If its base is too close to the wall, the ladder will be unstable and likely fall backward when you climb it. If it’s too far away, the ladder may bend or slide out from under you. The distance from the base to the wall should be equal to about one quarter of the ladder’s length.
Be sure that the ladder rests on a firm surface. As you climb or reach up, keep your weight centered. Do not lean out to either side, keep your hips between the rails, and never stand on the top two rungs.
When using an extension ladder to reach the roof, extend at least two rungs above the eaves. This way, you can hold onto the ladder as you step onto the roof.