My Paint Scheme

I finished a few squads using the Kabal of Last Hatred color scheme. I like how they turned out but I'm struggling with a few details. I decided to try for a "ferric mud" base by using Stirland Mud with a heavy drybrush rust color followed by a light bone color. I'm happy with the result, but the model is very dark overall. I'm looking for tips on how to brighten it up. I'm looking for anything from whole new base scheme (not preferred), to different rim colors or grass tufts. I'm thinking of light brown grass and a much lighter rim color, but I'm pretty terrible at predicting how the colors will work off one another.

Second question is on the brass pods for the guns. I'm not completely sold on it but I can't think of anything better.

Sorry for the shoddy photography

I like them alot!

For the bases light brown tufts sound great, but i wouldnt change the rim colour,
black looks good and i feel like if you do them brown it would just be brown in brown.
To make the models pop more i would either go a bit lighter on the eyes or the drug tubes (if they are drug tubes for you).
Maybe if you are into it you could paint the tube thingy in the rifles in a brighter colour but honestly i dont think its missing much, the light blue goes really well with the purple armor^^

I really like the blue and purple combo as well. Interesting that you brought up the drug tubes. Like the pods on the guns, I didn't really know what to go with for them. I keep thinking either a glowing or translucent blue or green. I don't really want to use blue because I already feature that prominently elsewhere. I'm avoiding green because of the Barney effect. Maybe I could tie in a orange type color to match the eyes and the hue of the base.

I really like the colour scheme. I do think green or brown tufts will brighten the base, but still keep the mud theme. And I also agree that the rim looks fine with black. A yellow would be a big contrast for the eyes and pods, however it might not be to your taste. Orange could work well also.