First some pictures of the sheet - I did take a photo before I started using them but seem to have lost that! I do have one sheet with only a couple of decals removed so mostly complete so you can see what comes on the sheet.
The first thing to say is it is a single decal rather than separate individual decals. What I mean by that is if you put it in water you would just get one big decal and from a practical point of view it means whatever size and shape you cut out the individual decals that is the size and shape of the clear surround (film) for the decal. A number of companies, particular figure makers or decals for wargamers, have this same approach. I guess it makes it easier to produce but it does mean you need to actually cut out the decal for the size of the film you want to get rather than just cut it out. I use some nail scissors as they are sharp and good for neatly cutting very small decals.
One thing to bear in mind is that when cut out they are very small and liable to be dropped and hence easy to lose. I use the inside of a jam jar lid with a thin layer of water for my decals and tend to cut them off above the water. Unfortunately they tend to adhere quite strictly to Murphy's Law and end up upside down! As I don't regularly clear out all the small bits of backing paper I need to keep an eye on it and flip it back over straight away otherwise you end up hunting for the particular small piece of paper that has a decal on the other side! This is particularly important with these decals as I have never come across decals that come off in water quite so fast - pretty much instantly.
The decals in the top left hand corner are for tank units and there are decals for a few different units which is good, but you only get 3 of a particular one. That meant I had to get three sheets to do a unit of four tanks with the same markings. If looked at very closely the colour is slightly grainy rather than solid but when on the model and looked at from even a foot away it looks a nice solid colour so no issue at all. Here is a P40 with the unit marking on the side of the turret.
There are also triangles which are used on Semovente and an example below:
I was not sure what the markings down the middle are for - in terms of type of vehicle - but when doing my Lancia Autocannone 90mm and browsing the web I found they used the centaur with bow on the truck door. The sheet handily had this and so I put on my trucks. Looks very nice. At first glance though they all face the same way on the decal sheet and should be pointing towards the front of the vehicle which ever side they are on. I therefore put the one on the left hand side the other way round (i.e. back of decal showing) and was pleased to see it is black throughout and not white on the rear of the marking so all good. Looks very cool!
There are a few other bits on the sheet I have not made use of and then the most numerous decal is the registration number. This comes as an almost square rectangle with part of the number on the top and the rest underneath and one with all the number in a single line. There are always two with the same number on but they are both the same shape. Checking up on Italian markings online I found that the rectangle is used on the rear and the single line on the front - according to the Flames of War site anyway. Not sure if this is strictly true and the decal sheet is therefore not quite accurate or if this is not quite the case and there is not such a clear distinction about what goes on the front or the rear. However, when putting the decals on models the rectangular version fits much better on the rear and the single line for the front so I have stuck with the FOW view of things. This means that my tanks have a different number on the front and rear but it is not that easy to read and I doubt anyone would notice - apart from the fact I have just announced it to the world.
Here are a few examples of the registration number decals in use (gets a bit dark down where the decals are but if you click on the photos to get the enlarged version then it is clearer):
Finally on an L6/40 light tank. Given the bump at the front and checking other models on the web the decal needs to be cut in half to go either side. Somewhat fiddly given the whole decal is pretty small to start with but works out well - particular care here about not losing the decal when cut out which is no mean feat even with my small hands.
For applying decals I did a tutorial some time ago which you may find useful.
For an easy way to see all my WW2 posts check out the WW2 Summary page.