Shim if necessary. Keep ladders away from electrical lines and pay attention to overhead lines when moving an extended ladder into position. Never attempt to stretch while on a ladder. If you can't reach, move the ladder. Always follow the manufacturer's recommendations for using their tools and materials.
Dull tools are unsafe and can harm the work.
Maintain your tools. Always work with sharp cutting blades. Unplug power tools before loading them, changing blades or bits or making adjustments. Never use any power tool in the rain. Never alter or remove the blade guards on a power saw.