Here are the colours I have been using lately to paint my Roundhead troopers. For buff you can use almost any yellow brown of varying shade, but I have found Vallejo ‘old wood’ to work quite well. I like to vary my colours so I mix in GW desert yellow. This yellow is good just used neat on the cross belts as it makes them stand out from the coat. The Game Colour skin tone is a new paint I used today and seemed to work well. It gives a slightly more deeper tone on the coats. I’m painting all these to be dipped with Army Painter so I’m going for lighter not darker shades.
There are many other buff colours I use, Foundry and Tamiya are good too, with the latter being a very pale, light buff. Hope this helps.
Below can be seen the ‘old wood’ and the ‘flesh’ paint together on the same figure. Subtle but still noticeable. The ‘old wood’ was used on the arms.