Step 1: A dull bit and a sharp bit
Step 2: My favorite sharpening tool
I bought this bit sharpening tool almost 30 years ago for less than $20. The same tool is still available at Amazon and other places, and it is still less than $20.
A Drill Doctor is a very nice tool, but it costs four or five times the cost of this tool. I do not sharpen bits often enough to justify the cost of a Drill Doctor.