LFO - Low-frequency oscillation (LFO) is an electronic signal which is usually below 20 Hz and creates a rhythmic pulse or sweep. This pulse or sweep is often used to modulate synthesizers, delay lines and other audio equipment in order to create effects used in the production of electronic music. Audio effects such as vibrato, tremolo and phasing are examples. The abbreviation is also very often used to refer to low-frequency oscillators themselves
De-esser - De-essing is any technique intended to reduce or eliminate the excessive prominence of sibilant consonants, such as "s", "z" and "sh", in recordings of the human voice. Sibilance lies in frequencies anywhere between 2–10 kHz, depending on the individual voice.
Mixing is a fairly subjective activity and can make the difference from a well/poorly produced audio recording. The diagram on the left shows an example of a panning plot for a band - it will of course be dependent on the band, the music, the song etc..
You can visit this web page for more tips on mixing.