What actions can you do, if a long-tailed keyword-targeted article does not rank?

Some of my articles rank, and some just don't move. I mainly write posts targeting a long-tail keyword, that has lower competition, but some traffic to it. What kind of steps can you take to improve the ranking? Would the following actions help?

• Heavily analyzing the article, finding parts that can be improved;

• Getting a couple of backlinks targeting that post;

• Simply waiting for a longer time (I heard it takes months for a post to slowly climb the rankings);

Right now I have about 30 posts, and only about 4 of them bring good amounts of traffic. Is this normal? Surely not every single article can rank on the first page, right? What else can I do to increase my chances of ranking higher with my other posts?