I'm sure a new soldier would also appreciate rolling up his sleeves if it was hot

6 Months into the campaign the old hands get all the surviving recruits into a circle and show them where the button on the cuff is. The soldiers in Poland and France did draw remarks because they had their sleeves rolled up, which was rather an innovation for military clothing at the time, oddly enough.
Rather then saying what a 'Vet' should look like here is some photos of what are most likely experienced soldiers, they don't have to be filthy and crusty to be vets necessarily, in Germany to this day a beard is considered 'un-soldierly' even if they are permitted. (from what i have read) even the vets would shave when they had a chance during the war.
In this photo of captured Germans from Stalingrad you'll notice they are beardless if stubbly.
Chinstrips, mm in the majority of cases you will see even the most veteran soldiers with them on, German helmets have vent-holes so there is little chance of a blast breaking your neck (something you hear, but I would like to see that tested on mythbusters or something). Although I have included a photo of a chinstrap up German.
Tried to get a sample of people clearly with some combat behind them. Quite a range from dirty/clean and rugged to tidy.
Russkis