For me personally, having a goal in mind really helps speed up the learning process. I have an uncle in Japan, and for me, that really helps in learning the things, as it give me some pretty great motivation. And as repeated multiple times above, there are multiple factors in your learning speed, so it’s different for everyone.
As for memorizing, I felt that the mnemonics made me feel really stupid and I chose to ignore it. However, I decided to try them, and it helped quite a lot, as your brain begins to make connections between things you know and things you don’t. Also, sleep sort of kills the studying, but if you study first thing in the morning, it helps.
And take everything with a massive pile of salt because I just started, haha! Hope this helps though.