To add to what has already been shared, I'd highly suggest checking out Andrew Loomis' books! They're free to read, and great 'how to' books! Humanae is a resource blog dedicated to cataloging the faces of people varying in age and race. I'd recommend it for learning facial structure and variety. Fuck-ton of Anatomy References is also a great resource, while this blog no longer updates it has great tutorials and anatomy diagrams. If you have some cash to spare and if you're alright with full (in your face) nudity, Anatomy for the Artist is an amazing book for learning structure and proportions through nude photos and the occasional muscular/skeletal diagram.
Lastly, Draw This is a Youtube channel dedicated to showing free online life drawing sessions.
You can also do life drawing anywhere else. People always associating drawing from life with paying for classes, but you could just go out and do quick sketches of people at the park, on the bus, on a plane, at the mall, etc. You can even sketch family members while you all are watching tv, or draw yourself in the mirror. There's nearly no limit to what you can do with life drawing.
Can't say much about how good my anatomy is now (I haven't studied in ages) but back when I was really pushing it my strategy was referencing classical realism paintings, nude photos, and people walking around at the mall and such.