Alrighty so this campaign is pretty damn easy on Hard, nothing in particular should give you too much hassle, though there are three points I would like to bring up so you are aware of it;
1: The first War story where you are a tank driver. Take this one slow and steady, just like everything else but I think it's probably harder here than what the foot sections are, most things take you down VERY quickly if you are not careful.
2: Just make sure you are doing it on Hard, for whatever reason my difficulty reset a couple of times during the campaign so just before you launch a new war story make sure that it is set to hard.
3:
*** Spoiler - click to reveal ***When it comes to the fight with the armored train for the love of all that is holy keep on the move. The mortars that are located at the front of the train will obliterate you if you stand still for too long. Take one or two shots from the field guns, lose line of sight and move to the far end of the field gun emplacements. There is obviously explosives located throughout the village and a rocket gun located in the tent to the rear of the village.
Overall a pretty easy, breezy campaign to do on the hardest. but in the wise words of the Aussie from the Gallipoli campaign: "Don't be a hero kid"
Give 'em hell.