How to practice a graphic design software?

This question is a follow-up of should I look into different graphic design softwares

I am starting to use Inkscape now, like many have suggested in that post.

How do I practice it?

I mean in GIMP I just started designing right away and learned along the way, But still I feel like I don't use ALL the features of GIMP properly, I was hoping to avoid the same situation in Inkscape. Is there anyway to practice properly like first practice drawing all the geometrical shapes, then shading... like that? Thanks.