Oh thanks for the tips guys I can really use them.
I must admit that this is a quite simplified vector. Only 3 tones are basically used.
In my next vector I will try to add more colors and more levels of contrast/color/tones/etc. I will try to use your way of vectorring Tavro. It sounds good, but posterize/threshold is really usefull for a beginner like me. It really helped me.

Thanks for the advice and we will see what the future will bring next!