Nan0 hopefully you can read english better.
The thing with realism is: You can't obtain it unless you take a photo of reality, so don't try to copy reality in polygonal models! It will be mish mash!
And since the only 3d graphics are either polygonal, or made of voxels (which requires unbelievable expenses to get an engine for that is only available within a certain few occupational fields), you will have to not try and copy reality. First, you need to look at the things you are making and judge them for yourself, not thinking about Nudl9's terrain.
Now, you must never be satisfied. What you make is never good enough for you. Next time is always better.
Next, you should try to see a scene in your mind before you place any doodads. Don't see it detail by detail. Don't think about where the doodads should be just yet, or which doodads to use. Simply picture something vaguely, from reality, or from your imagination. A nice setting. In this case, some awesome nature.
Now, try and draw the outline of your picture on the terrain with a tileset, as if seen from above with a bird's eyes. Fine, then you know where your treelines should be, where water should be, cliff/rock formations, etc.
Then start placing the stuff. I recommend starting with the things you feel are most challenging, or will be repeated the most, this warms you up, and the easy things will look better later on, than if you didn't take a challenge to warm up.
Don't place a doodad because it's a pretty doodad, it's not a model parade, place it because it goes well with the terrain below it and the other doodads nearby. Place it because you think that's the spot where it MUST be placed.
Frequently remove doodads you have placed. All the objects that look excessive or out of place; delete 'em. Leave only the details that your eye likes the most. Kill the unters, praise the ubers. Omg that was a bad phrase.
