You will really have to tell us more if you want a clear tip, Peter. Garbage in, garbage out, etc
. If you tell us which period of the war, for example, that'll be a good start. Then which season (summer, winter,etc). These will all make the difference in the uniform.
To add to what AlanL said, an early war distinguishing mark is the German high jackboot. This gave way to an ankle boot mid-war. Often (even in the early years), German troops (particularly recce and motorized) wore cam smocks over their M38 and M40 jackets, so you can't really recognize the jackets. Cam jackets were extremely rare early war too.
These are just basics, there are many more variables, and you'll actually save yourself time by hitting some of the sites like Feldgrau, where you'll see it for yourself instead of depending on us. Though we're happy to help
