I've recently started collecting Tyranids. I am not an artistically inclined person, nor have I ever painted models, but I have decided that I want a fully painted Tyranid army. My process description follows, my questions are at the bottom.
I assembled the bulk of my army by purchasing used models primarily from ebay, and have selected one of them to serve as an inspiration for my entire army:
However, I object to the idea that Tyranids hold guns and so instead have decided to paint the guns using the same colors that I am using for the body parts.
After extensive experimenting I've arrived at the following colors for my base coat:
Body - Cold Grey
Carapace - Gory Red
Claws and Teeth - Dark Goldbrown
Soft tissue- Goblin Green
The I "Dip" with this:
After experimenting, I have decided that I need to thin it a bit, and it is easier to brush it on than actually dip it.
Here are three models who's process is
complete, a Devil Gaunt, a Biovore, and a Genesteeler.

More Pics here:
http://www.dakkadakka.com/gallery/images-81431-40123_Painting%20Progress.html
I feel like these models look good, but also that I am missing a step. I've tried adding highlights and drybrushing, but find that using my basing colors clash with my final colors, and disrupts the shading / Gloss / Texture.
I've tried feathering by mixing 3 drops Gory Red With 1 drop white for the 1st level, and then 3 drops white 1 drop red for the 2nd.
I tried this both before I dip:
and After:
And I have been disappointed by the results. Also, I felt like my round tipped 10-0 brush was not up to the task.
Here are a few models that are base coated needing only final touchups before getting dipped:
Here are some questions I have:
1) I'm not 100% on my soft tissue color choice. Should I use a more vibrant Green? Is there another color that would match better?
2) Is feathering a worthwhile pursuit for my glossy style? If so, what am I doing wrong?
3) As I move on to larger models, do I need to add additional highlight colors? What colors would you recommend?
4) Should I feel ok about sitting pat on my post dip models? If not what should I do?
5) How do I photograph small glossy things like this? It was causing focus and lighting problems.
6) What suggestions do you have for basing that would go well with my color selections? I'm tempted to go with blackened destroyed looking earth.