Most current commercial Virtual Reality (VR) drawing applications for creativity rely on freehand 3D drawing as their main interaction paradigm. However, the presence of the additional third dimension makes accurate freehand drawing challenging. Some systems address this problem by constraining or beautifying user strokes, which can be intrusive and can limit the expressivity of freehand drawing. In this paper, we evaluate the effectiveness of relying solely on visual guidance to increase overall drawing shape-likeness. We identified a set of common mistakes that users make while creating freehand strokes in VR and then designed a set of visual guides, the Smart3DGuides, which help users avoid these mistakes. We evaluated Smart3DGuides in two user studies, and our results show that non-constraining visual guides help users draw more accurately.