Personally I prefer working with a black basecoat versus a white, but that is because I mainly work with darker colors and that means fewer layers. When I painted 40K I would try and do batches or full squads, but this is incredibly tedious and I would quickly grow bored. Painting Malifaux miniatures is more to my attention and paint style as I can focus on just one model since I know the next one I will be painting will be different and full of it's own character. Gives you more of a sense of accomplishment to look at a finished product, quicker gratification than trying to work on 5 at a time.
I highly recommend picking a color sheme for each crew you work with, nothing fancy just a few colors that your models will have in common. This will make it much easier when figuring out how you want to paint each model. Experiment with washes as they will help bring out shading and give different efects to the same color. For example I painted my Death Marshalls primarily brown, this includes their coffins, but I used the GW red wash on their coats, boots, and gloves to give it a leather look and I used Nuln Oil on the coffins to give a wooden appearance. If you have an old miniature around use that as your test model to see the different effects before you apply it to one you are actually going to paint.