If you've read the 20 rules for learning (and the write-up [here](/series /twenty-rules-for-learning/)), then you'll know about interference. Interference describes the effect where two pieces of information conflict in your memory, making you struggle to recall either of them properly.
The opposite effect is also possible. Often, learning similar or related information makes it easier to recall. This is because you're building a web of interconnected material, which makes it much easier to recall and use what you've learnt. You could call this complementary memory.
For example, it's easier to remember how to write a character when you frequently see it in what you're reading. The inverse is also true. Another example comes from knowing sets of words that overlap in the characters they use, or characters that share components. All these links contribute to better recall and understanding.
Taking advantage of complentary memory
Complementary memory can be used to your advantage when learning Chinese. You get the benefit of it when you learn from real Chinese text and audio which naturally contain links and relations. You can further add to the effect by actively seeking out complementary material to add to your repertoire.
Some techniques that work well for building complementary memory are sentence branching, defeat in detail and the rabbit hole effect. It's also good to seek out material that is related to what you're learning: related words, collocations, antonyms and combinations are all good places to start.
You can incorporate the complementary material into your studies through your daily input by reading releated texts or finding texts that incorporate the same vocabulary or grammar structures, or doing the same with the audio you listen to. This can be taken a step further when it comes to output: you can set yourself writing tasks involving target material, and aim to incorporate as much complementary material as possible. As always, communicating with native speakers is excellent as it naturally exposes you to complementary material in an active way.
Complementary memory and interference
One issue to be aware of when actively seeking out material to contribute to complementary memory is that you might accidentally create interference. That would be quite a shame as it's the exact opposite of what you want to achieve. The first rule of combating interference applies here: be aware of interference and try to notice it as soon as possible. From there, you can start using tactics to deal with it.
Interference frequently occurs when the way you remember something actually relies on something outside of the information you're trying to learn. For example, if your textbook or flashcard deck contains only one word related to aeroplanes, you may remember it easily just because it's “that aeroplane word”. However, once you learn more words related to aeroplanes, this route of recall doesn't work as well anymore and you get interference. The solution here is actually to increase the set of words you know related to the topic to ensure you're recalling the actual word or concept and not background information about where you learnt it from.
In this way, seeking out complementary memory is actually a good approach to dealing with interference. Expand your knowledge in the problem area and work hard on improving your active recall there, and the interference will go away.
This is not about memorising
As always, remember that learning a language is not about memorising things. Memorisation and memory-training may come into it as a way to create exercises, but they are always a means to an end with language learning. Those exercises provide an effective and consistent means to practice, building fluency and create active knowledge. You're acquiring a skill, not storing data. Using complementary memory is another approach to developing that skill.