Shank must be completely inserted into collet and then backed-off approximately 1/16". Don't "bottom-out" bit in collet. Never partially insert bit into collet. Tighten securely and recheck periodically for possible slippage or "run-out" due to wear. Keep collet clean and replace if worn.
Never start router with the bit in contact with wood.
Always feed your work in the proper direction against the bit rotation. Don't force feed the bit or overload your router, Feed at a constant moving speed to avoid burning the wood.
Do not face tool's discharge when operating.
Always unplug router when changing bits or making adjustments.
Use a router table and fence whenever possible.
Make sure your work piece is properly secured and use push blocks, sticks and featherboards whenever possible.
Keep all your bits, bearings and assemblies clean, lubricated, and securely fastened.
To avoid damage, store bits properly in a pouch, box or tray.
The bigger the bit, the lower RPM recommended (see chart).