I prefer telegraphy as operating mode. Consequently, membership in AGCW-DL is crucial. In this club, I manage the Activity week. As an elmer, I support newcomers and returners. I am one of the operators of DL0SLW, the lead station of the QRS network, which gives everyone the chance to operate in telegraphy at low speed.
AGCW is member of the EUCW. For the EUCW, I manage their diploma.
Of course, every radio ham should support the local IARU club. I am member of the chapter "Bingen am Rhein" (DOK K15) of the German Club DARC. I am not only engaged in the local chapter, but also in regional or central initiatives.
Other CW clubs I am member of are the "Netherlands Telegraphy Club", the "Straight Key Century Club" (SKCC) and the "Morse Preservation Society" (FISTS).
Communicating with low power is an art (and mostly connected to telegraphy). I am member of the Britisch G-QRP-Club and of the American QRP-ARCI.