You get flagged if you don't fall in line with the status quo. So always think positive, don't think negative. Never disgree with anyone. Don't be ironic or sarcastic. This may not be enough because if you downvote somebody, they'll revenge downvote you. You might also be randomily downvoted.
Unfortunately for me I don't fall in line, that's why I have a low reputation. I would also like to add: