I make a suggestion by the nice Diorama of Thor
but my question stays : what is important for a Diorama, nice looking soldiers, nice camouflage and details but clean or still realistic which is with all the details but DIRTY my opinion then is realisitsme is important for a good diorama.
Now your opinion please and not the fire squad OK

The most important thing in any diarama is the "STORY".
You must have a scene to show the audience. Regarding of the story, your style and taste there will be different things to focus upon.

I cant say how to do it generally but there are a few things that can easily spoil a good diorama.

Different finnishes on different subcets. The tanks are superb, the building is so and so and the figures are bad. The badly done subject drags all the others down. Allways see your work as a whole piece even when it cames to chosing base and a sign.

Just tell one story. Dont have several plots going on in the same dio.

Make sure that the figures really looks like theyre doing what theyre supposed to. Espicially when it comes to grabing things and interact with vehicles or other people. To do that less or more figure convertion usually is required.

Try to make it as small as possible. Ask yourself, what is the pieces that I have to have in my dio to tell the story.

Id say also that if an action is to be in focus theres humans doing the action and therefore its almos always the people that is the most important thing in a dio. Building, tanks, cars, planes, foilage etc just act as props.

Start to determine what story you would like to tell with the Mörser Karl and try to develop it further.

OK then you opinion is that a diorama has too look as realistic as possible, I agree but ( I don't mean to piss anyone off ) I sauw in this site a diorama of the Bulge ( Ardennes ) with if I remeber good a Tiger Tank on a muddy road,couple of soldiers ( kind of SS uniform ) a motorcycle the hole thing was great but I had the feeling that it was spoiled by the fact that every thing was clean has if they fall out off the sky very gently not a dash off dirt. And that was really to bad not realistic at all but very good job now what ius for you important then???

It all comes down to each modellers own taste. Some guys go to the extreme of superdetailing and dont want to cover all their work in dirt. Some then again hide their lack of work or mistakes by dirt. It is my belief that if all the figures and vehicles in a dio have the same finish it will still be OK. At the end of the day it is a modeller and artistic license is involved. But as long as the modeller is happy with their own work ..... it doesnt matter!

Im not sure what youre getting at Rima!
Isnt it every diorama builders intension and goal to get their scene as realistic as possible?

What people thinks is realistic varies a lot though.

The same goes for the story. Some think that loading a tank or marching to the front is a great story idea while others would prefer a more advanced plot. Yet others only like action dioramas.

Placing almost totally clean vehicles on a muddy road draws down the whole diorama when it comes to general impression. How much depends on the viewer and other aspects of the diorama. We must allways have in mind that this is a subjetive matter of taste. Which we who compete usually are very well aware of. Any builders is allowed to do what he feels looks good but one doesnt have to like it.

Making dioramas is almost like planning a painting or a scene setting in a movie. Theres a lot of artistic license involved. My general idea is that the artistic side should always win over the realistic and historical side unless it doesnt make the diorama look stupid or ridiculous.

Theres a lot of things we do that isnt realistic but so fully accepted within the hobby that it has become the norm. For example: Hands and eyes on most figures are way to big for their scale but it looks good when one can see the eyes and details on the finger. Another: If one should weather a tank realistic when it comes to mud and dust most people would say that it has been overdone.

The bottomline is that your first goal should be to please your self.
If you wanna win competions or be a guru, thats another story.

I would like to make an addition to my first reply: Make sure everything blends into the scene.

This is what I wanted to hear because i got in discusion with people about the diorama I mention and they were critics that make me ask myself what is then important. I came to the conclusion that the hole picture you put on a diorama the wolrd you create should be as realitic as possible and that mean also don't be afraid about make your figures as dirty as it should be. Take as exemple Film Saving private Brian what would you have thought about it if blood was gone such as the war film during the 50' s,60' s and 70' s. Looke at the Film battle of the Bulge nice Tiger ( American ) Tank nothing was real but suggestieve. Are we then doing the same in modelisme or not. Make a diorama as real as p[ossible is a question off owne meaning everyone is free to make hie/ her Diorama as he/she wants. But I prefer somethings which looks as realistic as possible

Depends. For military dio's, dirty is the way. If you want to show a Ferrari F1 or an oldtimer, you may want it all clean and pollished.