Fulgrim Fully Built - How to Approach Painting?

Hi all,

I have a Fulgrim model that's been sitting primed and waiting. Well, I didn't know people usually do him in a few sub-assemblies, and have been stressing about painting him correctly. Do you have any tips to painting Fulgrim fully built?

For reference, I do not have an airbrush and will be using a lot of contrasts. Thank you all, have a great day!