Virtual reality (VR) sketching tends to be democratized in the early stages of design for several reasons (e.g., improved creativity). Nevertheless, our field studies and the scientific literature identified some constraints to the use of VR sketching such as the low quality of the sketches impacting the acceptance of the design tool for the future users. The objective of our study is better understand them to improve the quality of user sketches. Thirty-one participants completed questionnaires (VR and drawing experience, visuo-spatial skills, usability) and performed 2 VR sketching tasks. Sketch quality was evaluated using a multifactorial approach (volume, proportion, fidelity). The results showed that each skill (visuo-spatial abilities, drawing experience and spatial inspection) has a specific impact on some factors. We detailed the results and proposed recommendations for improving the use of the sketching software and sketches quality.