There's still a lot for me to learn too. A lot of it depends on the kind of artstyle you want ? If you want real human proportions nothing beats just looking at actual bodies.... there's lots of videos with with general guidelines about where body parts go and shapes. If you're getting into finer details I think work out videos are pretty good for isolated bodyparts and movements. That being said i don't think 100% accurate proportions are that important but it helps to learn how everything works together