What is the best technique for achieving precise 45-degree miter cuts using a router bit?

The best technique for achieving precise 45-degree miter cuts using a router bit is to use a miter gauge or a miter sled to guide the workpiece at the correct angle while cutting with the router bit. This ensures accuracy and consistency in the cuts. Additionally, using a sharp router bit and making multiple passes at a shallow depth can help achieve clean and precise miter cuts.