The overall sonic texture of death metal can be dense and heavy. Choose carefully where and when to use your wah pedal in order that it will actually be heard over the other instruments in the band. Preferable song sections for wah-wah pedal use include breakdowns, anywhere the drums drop out, and bridges or instrumental solos where the overall texture is thinner.
The wah-wah pedal has a very distinctive sound, and is best used sparingly for this reason. If you use a wah pedal all the way through a song, the audience--and your bandmates--will quickly get tired of this sound. Use the pedal only in a few sections of each song and its aural effect will be greater.
The wah effect of the pedal has a rhythmic effect on the guitar sound, and it is possible to control the tempo and rhythms produced through the wah effect. As death metal is characteristically complex and fast in terms of rhythm, experiment with matching the rhythms produced by your wah pedal to the rhythms of the other instruments. Alternatively, create a rhythmic counterpoint by playing a different rhythm to the other instruments, in the same tempo. Both these approaches will make the music more interesting to the listener, as the rhythmic pattern of the wah pedal variously reinforces the rhythm of other instruments or complements them.