Actually I used "Not so random coast line" tut by RobA. This lead me to:

Click image for larger version. 

Name:	xTrain02 land.jpg 
Views:	91 
Size:	183.9 KB 
ID:	46188

Next I applied the "Using GIMP to Create an Artistic Regional RPG Map" tut, where I got the idea on how to add sea level.
Even if I didn't use exactly the same way, the result have been sufficient for me:

Click image for larger version. 

Name:	xTrain03 sea added.jpg 
Views:	95 
Size:	225.2 KB 
ID:	46189

In various tutorials, there have been pointers to the pattern usage, unknown to me till this tryouts:

Click image for larger version. 

Name:	xTrain04 grass land.jpg 
Views:	118 
Size:	287.1 KB 
ID:	46190

Oh yes, the mountains. Very mysterious area full of "Bumps" and "Embosses", multilayers, etc.
Here I read so much threads, that I cannot say which influence have been the most usefull.
Maybe the authors will see their techniques :-).

Click image for larger version. 

Name:	xTrain05 mountain.jpg 
Views:	88 
Size:	292.3 KB 
ID:	46191

Forest added using the pattern style:

Click image for larger version. 

Name:	xTrain06 forest.jpg 
Views:	117 
Size:	330.6 KB 
ID:	46192