>So the dominant strategy for staying at the top of a board is sometimes to be as controversial as possible. Basically, trolling.
In my experience this varies wildly, both from board-to-board and between imageboard sites in general.
One aspect is moderation.
The MO of 4chan moderation is to enforce US Law and a bare minimum of conduct in such a manner that it is not noticeable to most posters. If you use a browser extension which allows you to monitor deleted posts/threads, such as 4chanX, and have it monitor a thread where a poster is intentionally trying to incite controversy in a manner which is not conducive to the topic or board theme, they will generally get silently deleted. On their end, they may get warned, banned, or no notification at all, but the deletion is primarily effective because it deprives them of their exposure (also, ban evasion is trivial, while keeping one's flamebait up is not).
Another aspect is the culture of each board, which varies wildly on 4chan. For example, posting political and social flamebait on one of the slower, niche boards will just as likely result in people silently reporting the bait and not replying, or only reply to call out the post as flamebait (which is less ideal, but generally ends the conversation chain). If the content is deleted in a consistent and timely manner, the posters can establish norms, and can more effectively handle borderline flamebait without devolving into a flamewar.
Meanwhile, on faster boards, the larger number of trolls and people willing to take the bait, along with the ephemerality from faster pace of thread birth and death, results both in moderation being unable to keep up, and a need for more moderation, usually in the form of "janitors" (board specific moderators with limited powers). The more janitors, the more erratic the enforcement of rules tends to be, especially for Global Rules 3 and 6. So there tends to be greater animosity between moderation and posters on faster boards. The extreme examples would be /b/, /r9k/, and /pol/, the latter two informally serving as an outlet for (a)social and political posts which have proven to be irresistible to discuss while simultaneously being rancorous enough to derail almost any thread.
So to sum it up, trolling is more effective on the fastest and most vitriolic boards, and less effective on the rest. IMHO, the best "proper" ways to increase your exposure is to either post original content (with mixed success on a good day), actively engage others in conversation that is at least tangentially related, and if on a more image-oriented board, provide on-topic content to bump the thread.
In fact, 4chan officially refers to their analogous role as "janitors." "Moderators" on 4chan would be closer to Reddit admins.