Reddit reviews How To Draw Manga: Sketching Manga-Style Volume 3: Unforgettable Characteristics (How to Draw Manga (Graphic-Sha Numbered))

Here's what's worked for me so far:

Skim through Loomis books.

Do not use drawing on the right side of the brain or keys to drawing.

Pick up Scott Robertson's how to draw.

Practice until you built up good control over your lines and visualize shapes. (This step will probably take months.)

Do a shit ton of figure drawing (observation exercise only)

recommended: quickposes (site), croquiscafe (youtube), line-of-action (site)

After some exposure to quickposes with a focus on observation, you can now use michael hamptons book for more understanding/correcting.

Continue figure drawing (add construction now). Attend life model drawing if you can.

Learn/Study anime/manga style simultaneously:

Some resources for anime/manga:

https://www.youtube.com/channel/UCY-tGAhulrOzRd6n1mLZwSg/videos (Jp with eng subs, simplified contents to show beginner vs pro difference)

https://www.youtube.com/channel/UCRYuHKwhgfCighvhR3n151w/videos (jp no subs, anime gesture/perspective/anatomy, recommended to turn subs on cc and follow the videos as best as you can)

https://www.youtube.com/channel/UCDtAvTQ71BkcCS5CP7kbAeA/videos (kr no subs, art academy focused on anime, just see generalized techniques not too much content here; they also have twitter)

https://www.youtube.com/user/Newey02/videos (kr artist, explains anatomy, general process in simplified manner that you can kinda watch on)

https://www.pixiv.net/howto (behind paywall i think? sorry have membership so won't know, filter by top if you can)

https://www.amazon.com/How-Draw-Manga-Unforgettable-Characteristics/dp/4766118227/ref=sr_1_85?ie=UTF8&qid=1527533828&sr=8-85&keywords=how+to+sketch+manga (how to Draw Manga Sketching Manga volume 1-5, no longer making English version, but you can find translated pdf online and buy the raw jp books)