Some recommendations on painting grenadiers:
1. Give natural hair color. Hair was only powdered for special occasions.
2. Marching gaiters were usually black. Buttons on them were usually black as well. White was for garrison parades.
3. Not sure why the figures above have a natural color cartridge pouch – should be black. Belt was natural unless a buff unit (IIRC).
4. Braddock grenadiers would wear linen small clothes, not red wool (blue breeches for Royal regiments).
5. Turnbacks (skirts) of coats match facing colors in this period.
6. Haversack was linen so greyish in color.
7. There were buttons on the backs of coats (not shown on figures above). Depending on level of detail you are looking for.
Google Morier grenadier paintings for additional help.