If using rattle cans then Tamiya TS-61 'NATO Green' is a pretty good starting point.
It's good paint, adheres well, takes enamel or oil washes nicely. It's a tad on the fumey side, so good ventilation is must.
Vallejo 'Reflective Green 890' is a pretty good colour match for it (TS-61) for touch ups (well my decade old remanant is, colour could have changed over the years).
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If using an airbrush then Vallejo 'NATO Green' surface primer, seems to look the part.
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