1. Use the manufacturer’s frequency selector to find the best frequency range for your area. Sennheiser at http://en-us.sennheiser.com/service-support-frequency-finder and Shure at http://www.shure.com/americas/support/tools/wireless-frequency-finder
2. Once you have your products and are installing, the first step is to run the automatic frequency scan on the device. This will tell you the band(or group) to use, and the channel that is best to set the frequency to. If you have multiple microphones, manually set the 2nd and subsequent transmitters in the same Band (or group), and another frequency.
3. Using the method in #2, you will avoid intermodulation problems which cause drop outs. The manufacturers have calculated which channels in each band (or group) that will give you the best results without intermodulation problems.
4. Within the same band (or group), never use the same channel/frequency spacing, i.e., 1,2,3.
5. Never operate two transmitters on the same frequency.
6. Physically, keep the transmitters apart the maximum space that you can.
7. Use proper antennas, and either combining or splitting when necessary.
8. Adjust the power level of the transmitter to the lowest level that works fine – to prevent intermodulation problems
9. Allow 10-15′ minimum between transmitter and receiver to avoid receiver overload.