One question you could ask is why didn't I wait and do all the weathering at once? Well, I wanted the different parts (boots, coat, and sword) to have their own weathering history. The process is a bit messy and imprecise so not very easy to dab mud onto the boots or dust the coat while keeping the sword clean. It was much easier to just go in afterwards to add a bit of dust to the scabbard and straps.
For the plume I chose a two color pattern. There seems to be a variety of plume colors with not a lot of standardization among the regiments. My reference book mentions solid color options (white, red, or crimson) and multi-color options (green with regimental color, red and green, red and white, white and yellow, black with regimental color, green and yellow) and lists regiments that were seen with each. Based on my reading, I'd guess you could have any regiment with just about any of the plume variations. But sticking to a color-regiment pairing that is based on a historical reference, I chose to do white and yellow for the 22nd Dragoon Regiment (although based on the uniform he could be in the 22nd, 23rd, or 24th regiments).