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.
This is the best advice. The trick to keeping high karma is to cultivate your discernment. Each time you write a post, assess its value, and then delete it if you don't anticipate people appreciating it. View that deletion as a victory equal to the victory of posting a high-karma comment.
I would be concerned that you might post with popular opinion not with valuable or worthwhile ideas. (if the caveat of worthwhile ideas even if they sound unpopular is included then this is still a good strategy)
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.