Here are articles that are specifically aimed at helping fellow reenactors with improving their impressions.

Smoking and the German Soldier

Smoking was extremely popular in the 1940s, both in civillian life and the Wehrmacht. Heres a breakdown of what is authentic to smoke

Authentically Dirty

It seems that nowadays too many reenactors are simply too clean. Heres some pointers how to get that nice, field worn look.

The German Helmet Part 2