OK since there isn't a guide for this I'll make one.
Most of these are not too difficult to get 5 stars so I'll only post the ones that I had trouble with. If you are having trouble with any of these and I haven't given any tips for that mission, post a comment and I'll try to help you out.
To get more stars, you need to destroy enemy vessels and get more "tonnage" as the game calls it. Basically the heavier the ship, the more tonnage it nets you once you sink or damage the enemy ships.
First some general guide lines:
The easiest sub to get most of these is the Stingray because it has 2 torpedo tubes and it is the fastest at the lowest depth. I'll note the ones I used another sub.
I know you'll need to get 65 stars to get it first, but many of these are pretty easy to get 5 stars.
The way I got most of these was to stay at the lowest depth and pop up to periscope depth, shoot both torpedoes and pop back down.
For the missions that you need to capture so many ships, you can still surface, hit them with your deck guns until they have about 5% health of so and that should net you 5 stars easily.
Also during some missions after you've destroyed everything, they will sometimes send 1-2 bombers at you at about 1 minute intervals and you can increase your tonnage that way. Not in all missions, mind you, just some.
1 reason some of these are hard is you get help from your allies and they will destroy the enemies before you can. I recommend getting out in front of everyone to try to get them first. Sometimes you'll have to be pretty reckless to get them so also try to be careful.
OK here are the missions that I think need more info to get 5 stars:
Prologue, mission 1 New York Harbor.
That's right, the first mission.
This is, without a doubt, the one that gave me the most trouble.
You'll need to destroy about 60-70 planes in this mission and the score you'll need is 40,000. The mission is timed so when the last of the planes goes by, that's it.
I used the Patriot for this mission cause I like it's deck guns best.
The bombers ( red on the mini map ) are worth more than the fighters ( gold on the mini map ) 500 for the bombers and 100 for the fighters. They come in different formations so learn to recognize them. Whenever you have a choice, always go for the bombers. I had an easier time when I was facing towards them when they were coming at me. then if I needed to turn the turret to get a few extra planes, all I had to do was hit Y and I'd be facing them again. You'll have to figure out what best works for you.
I'll post a video of this one to give an example. This will be the only video I post of these missions.
North Sea, Mission 5 Escape
The reason this is hard is there are 2 mine fields and if you go through the second mine field too fast, you will get allies that will get the enemies before you can.
Here's what I did:
I used the Victory for this mission.
First, destroy all the enemies at the beginning. You can submerge at the beginning and all the enemies will come to you and most times stop and let you sink them. You'll get 35,000 or so for this, I don't remember exactly.
There are 2 sets of barriers at the beginning. After the second one is the first mine field.
If you stay between the first and second barrier they will send a bomber at you every 30 seconds or so that will net you 500 at a time if you stay between these. This takes a while.
I stayed til I had 50,000 while at the same time clearing out the first mine field. I made a pretty wide path because you will be attacked by air pretty much continuously til the end of the mission and It gets kinda dicey towards the end of the mission. That was why I used the Victory.
Then I stayed on the surface through the first mine field and tried shooting down a few planes til I got to the second mine field.
Then I had to submerge to clear out a little of the second mine field so I could get through. You need to stop about half way through the second mine field or you'll get some unwanted help.
Stay at extreme range of the enemies on top of the water and try to do 3 things at once. Clear the mines so you can sink the enemies, then torpedo the enemies while shooting down the planes. You need about 94,000 or so for 5 stars I think.
English Channel Mission 2 Foxchase
The reason this mission is hard is that if you don't sink enough ships fast enough they will get out of range and you won't have enough for 5 stars.
So first as soon as you spawn, turn Northwest and sink the big ships there, ignore the small frigates. They aren't worth much anyway. There are usually 2-3 oil tankers. Then go straight east fast.
1 battle ship will be leaving the cove. Sink that on the way by and continue past the cove. there are several ships going east that will go out of range. Sink as many as possible. There are 5-6. Once you get as many as possible, come back to the cove and sink the battle ships, then the rest of the ships.
It's not too hard as long as you've done the beginning part fast enough. There are several ships in the cove to get and if you don't have enough they send bombers every minute or so.
You need about 314,000 or so.
Those were the only ones I needed to work at, the rest were not too hard. I'll post a video of that first mission soon. If you need any other help, post a comment or send a PM and I'll try to help.