What does the literature suggest about the optimal strategy for quickly memorizing various types of content? I just finished reading Moonwalking with Einstein, a journalistic piece on the World Memory Championships. The book explicates the various techniques used by participants to memorize different types of contest materials-- for example, there are techniques for memorizing large lists of numbers, foreign language vocabulary, packs of cards, and poetry.

The Dominic System, for example, is often used for memorizing numbers, the PAO system is often used for memorizing for packs of cards, etc.

However, a lot of these techniques have not been rigorously tested in a scientific setting to determine which forms of techniques are empirically optimal. Often, they're just circulated in underground communities, without any objective way to adjudicate between the merits of competing systems.

I was wondering what the research on memory suggests is the best way to memorize the above types of content.  I suppose you need a metric to qualify "the best way", so let's say that preference is given to speed over duration of memory.   I'm in the process of learning a new language, so I'm also particularly interested in foreign language techniques.
The first and most obvious answer would be that repetition cements new information into memory. The second technique is that an event that involves a strong emotion will be more easily remembered then an event where little or no emotion is felt. If you are learning foreign languages, you could practice sentences or paragraphs in a dramatic way, like learning the lines of a play. This could be done verbally or non-verbally, but verbally would be preferred for the auditory feedback. Flashcards, mind maps, and similar tools would help with visual feedback, helpful as this article suggests. Handwriting and typing would help with tactile feedback.