I've heard drawing arrows serves at something so here I am

Hi, I am again picking up a completely different method to learn to draw and somehow arrive at gesture drawing and finally to anatomy. Here is the link, tell me how can I improve. Apparently I can't understand how to give them thiccness, so if anyone knows how to do that might be great.

https://imgur.com/a/tDQoyga

Thickness is to make the object 3d not just the space. ie:[img]https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR1kr35o2CHolg0KQPthSU5FEBa1jKd1UqfjEhdIRifll8pf4eLy1GMM-letnh1Na6LGE0&usqp=CAU[/img]

Your arrows look awesome btw