A pop filter is not essential for recording vocals, but can help attenuate aspirated plosive sounds—hard "P," "T" or "B" sounds that can result in a kind of popping sound when recorded—while protecting the microphone from moisture at the same time. Moisture protection is most important when using a condenser microphone, as they are extremely sensitive to moisture and are much more delicate than a cardioid microphone. For these reasons, it is recommended that a pop filter, whether manufactured or homemade, be used in most vocal recording situations.
Position the pop filter close to, but not touching, the microphone. Some pop filters are designed to be fitted to a second stand that can be positioned between the vocalist and the microphone. Most, however, are designed to be fixed directly to the microphone stand using a clamp or bracket. If adding the pop filter to a microphone stand, securely fix the bracket to the stand and then mount the pop filter.
Angle the microphone and pop filter to the 10 o'clock or 2 o'clock position. This will further help to prevent plosive sounds.
Record vocals as normal. The pop filter should not need to be touched or adjusted in any way during the recording after its initial setup.
Remove the pop filter after use and wipe it down with a soft cloth. This will remove any moisture that has built up on the filter during the recording session.
Pop filters are great for dispersing the quick blasts of air that result from vocal plosive sounds, but in general they also attenuate the high-end of the frequency spectrum. This isn't necessarily a good or a bad thing, but it is useful to remember. In general there is a greater degree of attenuation when using homemade pop filters.