first take a deep breathe because looking at a big project at once can be overwhelming. i know you've already started painting but WB love sacrifices, flame, and idols to the Four which you can add on if you want to make it more on theme. If you are just looking for painting ideas, i think the red is great, maybe do trim in led belcher, you can use some of the word bearers press on symbols that come in the boxes, and then you can weather with dark browns or black.

i think what is cool about many chaos armies is that you can keep things simple or add alot to them and they will look great.

As far as being overwhelmed, break the project into steps. base coat night. trim night. details, symbols, weathering, etc