If I have an issue, I do one of four things:
 
1.  Follow one de-esser plugin by another de-esser plugin.  After all a de-esser is just a frequency dependent compressor, and following one compressor with another is often a good approach.
 
2.  Split the audio and isolate the offending ssssss, or phhhttt, or tttuhh.  Put a de-esser on the clip FX.
 
3.  Same as #2, but export the wave and process in an external wave editor, save, and pull back in.
 
4.  Do the old "Get back in the vocal booth and try not to slobber so much!"
 

I find that if there are cymbals in the drum part this tends to create the effect of sibilence on my vocals even if it wasn't noticeable when the vocal is solo'd. Does anyone else find this?  Is it psychological or is there some physics/accoustics explantation?
 
To cure it I either edit the drumtack to remove splash/crash in the offending part of the song (normally the chorus) or else sidechain the vocals into a compressor on the overheads track to duck the cymbals when the vocals are active. 

richardskeltmusic
I find that if there are cymbals in the drum part this tends to create the effect of sibilence on my vocals even if it wasn't noticeable when the vocal is solo'd. Does anyone else find this?  Is it psychological or is there some physics/accoustics explantation?
 
To cure it I either edit the drumtack to remove splash/crash in the offending part of the song (normally the chorus) or else sidechain the vocals into a compressor on the overheads track to duck the cymbals when the vocals are active. 

Personally I rather get a great take than messing with fixes.
If the Cymbals are problematic, then do they belong there?

I think this is one of the biggest issues with project musicians, does the song need EQ?

For example. I used a RODE NTK to record my song (link below) and because this mic is so bright on my voice, I decided to add only around 200hz eq to give it some body. Meaning I added no high or mid frequency.

Please note: I am not implying you are not a pro, I am simply saying sometimes, just keep it simple and try getting a great take because fixes can be like plastic surgery, it will begin to become apparent. 

Heavy handed compression can also create sibilance on vocals
 
Toggle it in/out to see if there's any improvement (assuming your vocals are compressed)

Wow, plenty to be getting on with there!
 
Thanks to all!
 
rev