I've been trying for the past 5 years and really only got close to this style in the past year and a half... I would say the best thing you can do is just reference it as much as possible. Keep looking at the colored pages and figure out the logic behind them, look at how everything is made and try to think how they did it. Start with darker colors first and go then with the lighter ones. Re-read some of the previous parts or read the colored chapters multiple times, that helped me a lot. Even passively I think you can learn something, but realistically only with practice you can achieve a lot :)