He certainly looks determined

There are many methods. Two that I find quick/easy/acceptable quality for doing masses of guys:

1- Paint all the flesh a red brown. In Citadel terms it would be Bugman’s Glow, although I have Vallejo Saddle Brown. The exact shade is unimportant. Then layer on the normal flesh color to raised areas. Looking for about 70-80% coverage with the darker red brown in the recesses and crevices. You can continue to highlight up from there but for mass troops this is fine. A dot of black wash in open mouths and put some bone color on the teeth.

2- Paint the standard skin color on and give it an all over flesh wash. I wouldn’t use Agrax or similar for this as it is much too brown. A red-brown wash, such as Citadel’s flesh wash is more appropriate. I have made my own wash out of brown and red inks for a similar purpose. If it is applied too heavily, cleanup with the original skin color paint to bring back the tone may be needed. Highlight additionally to taste.