Write interesting hubs that will help people. Readers tend to want to thank the author (or show appreciation) for help and useful information. However, writing about something controversial can also draw out comments ... but, be warned, they may not all be good.
One important aspect is to communicate with your readers. If you can get to know them and 'make friends' .... then you will definitely get more comments. But, you also have to 'give' too remember ;-) ... so go make some comments on your follower's hubs.
Like the old saying 'what goes around, comes around'.