My usual vocal processing chain consists of several stages: Gate, EQ, Compression, De-Essing, and reverb (as a send).
This is first in the chain so the gate has the full dynamic range of the original audio. The more natural the dynamic range available to the gate, but easier it is to set the threshold and timing for a natural sound.
Generally I prefer to use EQ before compression. This is so I can get the tone I want for the mix before I adjust the dynamic range. It also makes it easy to highpass the audio so the compressor doesn’t respond to low-frequency audio (such as rumble) that isn’t going to make it to the mix anyway. I’ve written more about the order of EQ and compression here.
I choose to apply compression to the final tone of the sound, rather than adjust the tone afterwards. This helps the compressor react smoothly and naturally to the sound we hear, rather than responding to sound that is going to have its frequency balance changed afterwards.
I don’t often use saturation of vocals. When I do though, it’s just after compression, and I use it similar to a limiter – to catch the few peaks that are too loud even after compression. Usually I set it up so that loud sustained notes are saturated, making them sound loud without overpowering the mix, but most notes are left clean (not saturated).
This is interesting. I’ve found that I get the best results by applying the de-esser after EQ and Compression. I find that the way I use EQ tends to enhance sibilance (tonal tilt toward high frequencies and high-ratio compression). Using a de-esser earlier in the chain sometimes means that the later EQ and compression counteract the effect of the de-esser. This forces me to apply more de-essing, which ends up sounding (more) unnatural (at extremes, it can “pump” a bit – but not in a good way!). By de-essing after EQ and compression, only a silght amount of de-essing is needed.
Reverb can be quite sensitive – responding to both tone and dynamics. In the kind of dense productions I usually do, it’s best to feed the reverb as consistent a signal as possible, to avoid widely-warying levels of ambience or a build up of mud. The purpose of reverb here is to add ambience and air to the vocal sound – not to be heard as an effect separate to the vocal. To that end it’s important that the reverb responds to what we hear (similar to the compressor). I’ll often lowpass the reverb to keep it sounding lush and avoid it “catching” any sibilance.