Multi-blade props follow the same basic principles -- increase pitch & decrease diameter for speed, or increase diameter & decrease pitch for acceleration/climb. However, multi-blade propellers have their own particular applications. They are generally used for scale appearance, or where aero-braking is wanted, or low noise is a desired outcome. A very significant application for multi-blade props is the case where physical space limitations constrain propeller diameter & a two-blade prop can't adequately transmit the available engine power within the diametral limitation.

There is usually a performance loss with multi-blade props relative to two-blade propellers, but sometimes the multi-blade prop is the only available solution to the problem.

I have a comment relevant to bkdavey's post. For mid-size engines (40 - 90 size) and 2-blade propellers, to retain approximately the same engine load, a 1" change in diameter is roughly equivalent to a 2" change in pitch. For example, a 10-6 is equivalent to an 11-4, or an 11-6 is equivalent to a 10-8. Propeller disc area increases as the square of the radius. Additionally, the greater wetted area and frontal area of the longer blade increases parasitic drag, whereas a pitch change only affects the blade angle of attack (lift & resulting drag). That is not to say that Brad is incorrect in his recommendation -- the variation in power load with a 1 - 1 change in pitch & diameter is not large, & a 1 - 1 change is a common starting tactic when experimenting with propellers.