Hi Swampat, it's Fabio here from Rome. Saw your sketches, I think I could not tell you anything on techinques since my drawing skills are less than half yours! I also practice gesture drawing daily, just to share with you my impressions I noted that you are using some kind of pen to draw these sketches, looks like some ink gel, is it correct? Have you ever tried these exercises using some brown tones pastels or even some graphite stick?Or do you think that for some reason it is better an ink pen?
Note that I ask you these questions also to learn something myself.
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