What you need depends on your system. Audyssey, YPAO, Anthem ARC, RoomPerfect and Trueplay use the microphone or phone that comes with them. Dirac Live and REW need a calibrated USB measurement microphone. Room treatment and extra subwoofers improve results with any system. These guides explain what to look for and why.
Measuring
REW Measurement Kit
The microphone, stand, cables and software you need to measure your room with REW.
Dirac Live
Choosing a Microphone for Dirac
Which USB microphones Dirac supports, calibration files and how to set the input level.
Bass
Multiple Subwoofers
Why two or more subwoofers give more even bass across seats, and how to place and wire them.