the big problem with miniart 1/34th military figure was the head.the detail is not very good,if not dissappoinrment.
Is there anyway to improve the face,thinking of using using micro chiesel to rework the face,but where do I start?

Richard,
Rather than take a chisel to the face you might want to try resin head replacements. There are a number of companies that produce some fantastic replacement heads to fix the exact issue you have. Don't know which nationality, etc. you are working with but you might try Hornet, Alpine, or something from Ebay which can be purchased for a fairly affordable price.
Cheers,
Rick

I have often used Mr Surfacer 500 to improve facial features of plastic figures. I put small dots on the places I wanted to be better visible (cheekbones, chin, nose, eyebrows etc.) The edges of the dots level out nicely during drying and so blend the dots into the original surface well.

I also recommend the resin replacement heads. I have also improved some plastic faces by careful use of a hobby knife and dremel style grinding ball bits to hollow out cheeks and remove pounds of flab from faces,etc.
J