Some of this stuff you may already know. I tend to believe that jumping in head first can be overwhelming for some people and sometimes a slower gradual process that leads up to direct study to be more satisfying.

"Draw from Life" is something that is tossed around a lot these days on the internet, usually at some one who shows a bit of flatness in their drawings, and it's usually thrown by someone who in the same boat as them. The idea here is to escape the flatness of still 2d pictures and draw real 3d in all it's wildness. While the intentions are good the expectations aren't always met.

Traditionally, drawing from life meant letting nature be your teacher, to observer critically and to note your own personal observations. What's not said is all the learning that took place before leading up to the need and the ability to observe directly and draw. The early learning is the foundations for which drawing from life uses.

The foundation, or the fundamentals, or the core knowledge, are always relative to how you draw. They're not well define for reasons that can discussed later. But nearly every single method or approach hinges on one thing: it's all about seeing relationships and their designs. From that kind of seeing the art of drawing emerges

Start with some still life drawings. Once you're well established with your foundational knowledge it may be best to start with inanimate objects like shoes or plants or sculptures etc. Set them in simple lighting. You may want to use a cardboard box and some boards to control the lighting better. Use whatever approach you like. Take note of your own discovers and build off those with each new still life. After your new way of seeing becomes second nature to you gradually introduce living things. You may want to look into finding a club or a school that hosts open life drawing studies. Or simply go outside if your into natural scenes.

The process is gradual. Practicing core things to get a good understanding of how they work and then observing still things to learn how to apply them. Gradually you should lead up to applying your artistic sight to real living active things.