When going on a trek it is a must to have a track already planned and the duration estimated.
For making GPX traces that you can import to CoMaps you can use GPX Studio
These tools are quite handy, however it is nevertheless recommended to carry a physical map as a backup.
You should map unknown places that aren't on OSM using GPX traces. You can do so with CoMaps or GPSLogger.
These tools record your position every once in a while and output GPX files when done.
telnet mapscii.me