Number 1 was my jotting down an idea without using any references - the goggles, the weapon that the Ninja Turtle Raphael uses when he doesn't have his sai(s), or Tsuyu Asui herself.
Then I went to youtube for a reference, but this time I used a freezeframe where she's not facing the right way or with her arms and hands in the position I wanted to draw - it was more to see the proportions and locations...such as where the straps came together, or finger length, or where the goggles sit on her head.
3 & 4 & 5 were jotting down on-screen elements to help get the proportions right...though even that doesn't always work, as the index & pinky fingers of 3 demonstrate.
But they did give me the idea for
6, which is based on the principle that its canon that Tsuyu Asui can hold things with her tongue...so I put the hand weapon in her tongue. Which led to
7, wherein she's using one hand to hold on to a pipe or something above her head, while gripping the weapon with her tongue. (Can she shoot out her tongue at someone, when the tongue is already out to some degree?)
8 was just my being silly...I thought "she has a frog tongue - what if someone had three frog heads: corresponding to the actual head, a right arm, and a left arm - and they each have that sort of supertongue".