I've played this game for a number of years and decided to write a guide about the various missions. I also address some bugs that occur in some of the missions and how to do the workarounds.

I have uploaded a series on youtube but can't post the link due to forum restrictions :(

Mission tips
Spaghetti airfield
There is a bug where the documents don't spawn correctly on Hard and Very hard. This requires you to restart the mission if it does not spawn correctly. There is a 33% chance that it will spawn so it will require a lot of restarts. Your best option is to drive immediately towards the tents to see if it spawns there, then restart if they are not visible. Even if you lose a couple guys attempting to check the documents, it's worth to keep going as you will get reinforcements on mission 4.
Babe in the woods
The driver will not surrender on very hard. In fact all auto surrender is removed and the only way to get a uniform is by shooting the germans hands and hoping that he drops his gun. It's about a 5% chance to drop so you're best option is to try to disarm one of the guards at the start of the mission.
Gameplay tips
Understand the vision mechanic
The number located on your unit card at the bottom is the distance at which enemies will see you. It depends on the lighting of you character, what surface they are standing one, the stance, and if they have shot. The moment you shoot you will get lit up and enemies can then see you. But you can abuse this by learning to shoot, stay prone, wait for the distance to drop and then take the next shot.
Grenades
Grenades are incredibly powerful and a great way of getting an extra edge against the Germans. Grenades allow for you to kill enemies without shooting. They have a wide blast radius and you can distract enemies with them if they don't know you are there. I find the fuse timer grenades (no 36) better than the auto explode versions as you won't die instantly if you mis throw, they have a larger blasat radius and can be thrown further.
3rd person camera
Abuse the camera as much as you can. When you cannot save you have to make every engagement unfair and peek around the corner to make sure it's safe to come out.
Accept deaths
Don't try to save every one of your guys, it's not possible as the AI will occasionally insta kill your guys. You have to accept the losses and move on. Throughout a campaign you will receive reinforcements so while you start a mission with 2 guys, on the next one you will get another 2 (with a bunch of random weapons).
Avoid stealthing
Stealthing in this game is very inconsistent and leaves you at a disadvantage as the firepower of the sten and de lisle is low. It's best to take better weapons and if you want to reduce the sound you make then only equip 1 of your units with a stealth weapon. Also realise that sound doesn't travel very far. You can have a massive firefight only for units 100m away not realise at all.
Don't rely on your teammates
The AI in this game needs specific conditions to be effective. They need to be at range, good line of sight, preferably prone to be able to hit enemies and not die. The moment things get close your teammates become basically useless as they can't hear gunshots or react in time. Their pathfinding also isn't great and you will find them wondering off into the wrong areas (Lighthouse is a good example).

Babe in the Woods was my Vietnam.

Did my first playthrough on Very Hard over a decade ago, that mission tripped me pretty hard. I think it took me better part of 4 hours of grinding that first patrol. And the only hope I had was a single comment in the ass end of some random dingy forum mentioning about it.