I've noticed several ways to maximize karma, and since the recent launch of Good Heart tokens, I've become convinced that I should share these with the community, because they will surely lead to better quality content. The tips are listed here and explained in the comments below:
Feel free to add your own in the comments!
Note that if you want to upvote this post without giving me net karma, you can downvote this linked comment or this one.
I thought it was unfair that Thomas Kwa had -17 Good Heart Tokens, given the valuable content he has shared in this post and its comments, so I took it upon myself to restore his positive-good-heart-token balance with a few strong upvotes. 
Of course, I only actually did that because I expect Thomas to split his payout fairly in this acausal ultimatum-like game (otherwise I would have refused to upvote his comments, resulting in neither of us counterfactually earning $). So, after giving Thomas 25 Good Heart Tokens, I am now waiting for him to send me $12.5 to my Venmo account.
If you split an idea into multiple posts, keep in mind that Less Wrong has a limit of five active posts per day. However, the restriction appears to be for active posts only. You can move one from public to drafts and make public a new post provided the total doesn't exceed five.
Split good ideas into multiple posts and comments.
If you write one post, you can get at most one strong-upvote, whereas several comments allow you to collect one strong-upvote each for much lower effort. Even if one of your ideas is good, a single post could be so long that the average quality is perceived as lower, and you only get one weak upvotes! At minimum, one should separate points that don't have an obvious place in the post into a self-comment.
Write listicles, especially with titles of the form "X Tips for Y".
Listicles are a time-tested clickbait technique, and more clicks means more chances for votes. Compare one of Ben Pace's recent listicles to other curated posts; the thoughts are good, but both Ben and I strongly suspect the listicle format made the material more accessible and resulted in more karma.
When writing humor, make self-referential jokes
When writing my last two April 1st posts on the EA forum, I knew that my strength in creating humor was mostly in my particular style: dry humor in the format of a serious post, which intersperses accurate information with absurdity and self-referential jokes. Other people have had success with announcements, but if I wrote an announcement it would very likely be worse.
Caveats: I think this tip might be less good (result in fewer Good Hearts per unit of effort) than other tips. This is because it optimizes the quality of the post, and you generally yield fewer Good Hearts this way than by optimizing Good Hearts directly.
Write low-effort posts.
Few posts will get more than about 300 Good Heart tokens. If writing one of these takes 20 hours (say 10 hours of research, 6 hours of writing, and 4 hours of editing), but you can crank out a moderately good post in 1 hour, that post only has to get 15 Good Heart tokens for you to break even in Good Heart tokens / hour. This is much lower than the median of about 20-25, and the skewed distribution of Good Heart tokens means the expected value is substantially higher than that.
Write about current events, rather than topics that have timeless utility.
Most posts will get most of their Good Heart tokens while on the frontpage, which only lasts 2-4 days depending on quality. It's ill-advised write a post that people will remember for years, even if it deeply inspires them, develops a new rationality technique, or does something else extremely valuable, because you won't capture most of that value. Worst of all are posts that are only appreciated in hindsight.
Note that the FAQ says the following about frontpage posts:
Frontpage posts must meet the criteria of being broadly relevant to LessWrong’s main interests; timeless, i.e. not about recent events; and are attempts to explain not persuade.
Non-timeless posts are much less likely to be frontpaged, resulting in less visibility.
If you want to upvote this post without giving me net karma, you can downvote this comment
or this one