Start putting volume on your figures. Ribcage, pelvis... For getting better with the torso it may helps to think about the belly as a ball connecting the pelvis and the ribcage. It also helps with understanding the flexibility of the torso.
Another good thing is to start with the proportions of the body, at least with the torso. Try to get a feeling where the nipples (one head below the chin at a 1:8 Head to whole body ratio), the slimmest point (two heads) and the hip joint (three heads) are.
