Good morning Viorel,
I use the fibres they use in gardenpondfilters. I cut them in very very small pieces, about max. 5 mm and collect them in an empty shoebox or something like that. I glue them with aircanglue( "BISON")( glue that you can spray out of an aircan..) and only on the outside of the twigs. Becarefull...not to much
And than I add the small cutted fibres on it, just let it fall gentle over the perepherie of the tree. Than I twist the tree between my fingers holding it at the groundpin and you can see that most of the fibres will "fly"away..
Mostly you have to help with your fingers and pair of siccorsto shape these small trees.
If the tree has become wwhat you have expected I paint the tree with paint out of an aircan(aerosolpaint? )Because it is scale N I prefere to use also ,after glueing the fibres, grassfibres from Noch or Busch or Faller, most important is: not to big grassfibers...I glue them too with a little bit of aerosolglue. After adding these grassfibers the tree is ready to be "leaved"
You can use the Woodland fine turf or the "micro flocken from Noch or anything that is not to rough for trees in N scale And it is also a matter of taste, or where do they grow: at the front, almost before your eyes, or in the background...
These are things you have to find out by yourself on your own layout. If you understand the german language just look at: >
www.pikoman.de < Apfelbäume) or: >
www.matthias-modellbahn.de <
wish you lot of succes..Jos
p.s. add two pict. pict 1:tree with blue fibres= rough and pict.2 :shrub with white fibres/or green = fine