The BZ Toolbar is a "go-to" for modeling organic or non-linear structures: Bezier Curve Tool - Extensions - SketchUp Community
One of the biggest benefits is the ability to adjust curves after they have been drawn. You can move control points to refine shapes without having to delete and redraw them. sketchup bz toolbar
Creates a curve that does not necessarily pass through all control points but is exceptionally smooth. The BZ Toolbar is a "go-to" for modeling