In basic terms, climb to full throttle altitude. ie. roughly the point where to set any reasonable power setting, you have to have the throttle fully open (there is a far more scientific description, but I've forgotten it and can't be bothered to look it up). Then, using the manufacturer's book, set the RPM & mixture. From memory, the IO-470 as fitted to the Cessna 206 could be set up in a multitude of ways. The one that used to float my boat was running over square (where the RPM was less greater than manifold pressure) for example: 23" and 2,100 RPM and leaning "lean of peak". Worked for me for a few hundred hours "Downunder".
But the important thing is, read the manufacturer's book.
PM