I think Zeev and Harel’s Israel hiking map is going to hit big (once they find a high-capacity server).
Hikers, bikers and Jeep drivers in Israel are used to this format and are tired of paying exuberant prices for the Simun Shvilim maps.
The big problem now is coverage.
Although we have most of the hiking trails in the database, only a small minority are colored.
This calls for a concentrated tagging effort from our community.
Can we arrange something? What do you think?
Each time I hike, I take note of trail coloring, but I have no clue how to tag this.
Can somebody give a short guide on this?
It’s explained here: http://wiki.openstreetmap.org/wiki/WikiProject_Israel#Main_conventions
You can identify trail colors in the mapa.co.il topographic map, and in the nature preservation society Arcgis server.
I don’t know how you learn the ITC reference number.
Also, it would be useful if you could quickly copy relation tags as you do for regular map features.
Same explanation with all possible values can be found at: http://www.wanderreitkarte.de/symbols_en.html
But I still do not understand how 
became osmc:symbol = blue:white:blue_stripe:orange_stripe_left
Will appreciate any explanation
In short, it says that the main color for the symbol is blue (which is incorrect BTW), and that the symbol itself has a white background with two symbols at the foreground: a blue stripe (in the middle), and an orange stripe on the left.
An alternative detailed explanation can be found at the OSM Wiki on Key:osmc:symbol.
In general, search the OSM Wiki for any tag and it can get you started well.