rest the base of ladders on firm, level, dry, non slippery surfaces away from hallways, passageways, doorways, driveways or heavy traffic areas.
use leg levelers or mudsills when necessary to provide firm support
keep the top and base areas of ladders clear of any obstruction
to provide the correct angle so extension ladders won't slip, place the base of the ladder one foot away from whatever the top of the ladder leans against, for every four feet in height of the ladder
To check, put your feet at the base of the ladder and extend your arm straight out. If you can touch the closest part of the ladder without bending your arm, or bending over, the ladder is at the correct angle. If not, the ladder is not at a safe angle