Promotion is not done by the author. The only reliable way to write a promoted post is to start a Rationality Quotes thread or to announce a meetup. Nor do insights come on demand.

People are clearly more comfortable with writing posts in the discussion section. It may be caused by loss aversion with respect to karma and perceived higher standards for the top level posts. Telling that we should write more will probably not fix that; it is analogous to saying that the criminals should be less immoral as a reaction to complaints about high level of criminality. While the criminals being less immoral would solve the problem, it is so unlikely to happen soon that this solution can be rejected as counterfactual. We should seek an institutional solution instead.

The problem consists of two parts. First, there are too much meetups to fit on the main page, and second, there are too few promoted posts. The first part may be solved by creating a meetup bar somewhere above the recent comments bar or a special meetup section. The demand was expressed several times lately and I think there is enough consensus that people who can code it can just start. (Better first propose one concrete implementation and vote on it.) For the second part, I suggest:

1. We have criteria about what is unsuitable for the main page, but everything seems suitable for the discussion section. No wonder the discussion section is a safe bet. Longer coherent posts should be demanded to be placed on the main page.
2. Write down (for instance on the wiki) that criteria specifically. They should not be vague as "high quality insights", but rather specific: Length at least 30 lines - main page. Shorter than 10 lines - discussion. Only links - discussion. Open conjectures - discussion. Explanations of finished ideas - main page. Meta-discussions of internal LW workings - discussion. Or so.
3. Automatic promotion based on karma (e.g. after receiving 15 or 20 karma, promote). Promotion of the lower-karma posts still possible manually by the administrators.
4. Reconsider the ten-fold karma multiplier for the main section posts. Its intended purpose might be to encourage high quality posting on the main page, but actually the frequency of the main section posts has decreased after the change was made. It is quite probable that risk aversion may play a role here.