Witnesses are responsible for three things: Upgrading the software when there is a planned upgrade; upgrading in the case of a hardfork (emergencies/hack); and providing a reliable price feed. Source
I'll be frank.
As a minnow. I don't have much influence.
Under the Selectorate theory I would be considered an an interchangeable.
I have some say in the governance of Steem, but I alone cannot influence its govenance.
However, top 19 witnesses have influence over Steem's governance, and blocks of us minnows can of course direct Steem's governance, in part by voting for witnesses.
My approach is to consider a witness whose vision for Steemit is most aligned with mine, accepting any trade-off in my exact desires as the cost of lower general influence (e.g SP), and endorse him.
While Steem's direction won't be perfectly aligned with mine, it'll be closer to it than had I tried to influence Steem governance relying only on myself, that is relying on my little influence.
If you've never used steemit.chat, here are the instructions:
#welcomechannel/join #trollsHow does the "witness" thing work, anyway?
It's pretty much the same thing, except that it's a voluntary process.
Yeah, I probably won't be leaving the site, because of something like that. But I probably won't be spending time on it either. <.<