I dont actually recommend staring off with a cube. Because especially in beginning you tend to shift to whats called box modeling syndrome. Usually when you finally DO ditch the cube your actually able to get rid of this fact, and eventually able to block it out of the cube anyway.
So my recommendation is following:
Block shapes of the body with simple nurbs objects don't mind if they aren't interconnected his is only a guide to get you going if you have a 2d drawing to block the volume on even better. domt be scared to overlap or shape them quite accurately the better the shape the more cloesly your points hit the eventual spaot without tweaking.
Now make these objects live and start drawing faces on them in a good edgeloop fashion, even if your uncertain what that is you tend to naturally flow along muscles and follows eventually anyway.
Thren sculpt a bit on top of this.
This is at first glance a much work way but it is a much more intuitive way to go about understanding why you lace points at where you place them.