Electricians prefer fiberglass ladders which will not conduct electricity and are lighter to carry than wood. Watch out for those power lines. Electricity can come down a metal ladder at the speed of light. The ladder should be placed on level, solid ground. The ladder should extend two feet above what you wish to step onto.
Stepladders stand on their own.
Extension ladders need to lean against something. The base of the ladder should be placed a distance from the thing the ladder is leaned against equal to one fourth the height of the ladder from the base to contact with the building. For example, you have a 12-foot ladder that you are leaning against the edge of the roof. The point of contact with the roof is 10 feet off the ground and extends out 2 feet from the side of the house. Therefore, the base of the ladder should be 4.5 feet from the wall of the house.