As I said before, I think it would be good if you get in the habit of trying to predict the votes that your posts get beforehand and then not post when you think that a post would produce negative karma.

One way to do this might be, whenever you write a post keep it in a textfile and wait a day. The next day you ask yourself whether there anything you can do to improve it. If you feel you can improve it, do it. Then you estimate a confidence interval for the karma you expect your post to get and take a note of it in a spreadsheet. If you think it will be positive post your comment.

If you train that skill I would expect you to raise your karma and learn a generally valuable skill.

If at the end of writing a post you think "I’m not sure where I was going with this anymore." as in http://lesswrong.com/r/discussion/lw/mzx/some_thoughts_on_decentralised_prediction_markets/ , don't publish the post. If you yourself don't see the point in your writing it's unlikely that others will consider it valuable.