Felicity, HubKarma relates ONLY to the amount of linking you do to other Hubs, both your own Hubs and other people's Hubs.
Nothing else counts towards HubKarma - not participating in forums, commenting on Hubs, or reporting. Those things contribute to your Hubber score and your Accolades.
Excessive linking can make your Hubs look as though they have blue measles, which is annoying to your reader, so I have yet to see any good reason to chase a high HubKarma score.
My HK is 80. I link to my own Hubs a lot, which counts. For instance, if I write a Hub on belly dance, I'll add an RSS feed to my other belly dance Hubs. If I join in a HubMob or similar challenge, I'll add an RSS feed to the other Hubs in the challenge. That's all I do. I don't use the link suggestion tool at all.