Cosplays

Hello. I am quite a new player to league, and I have grown a strong bond with some champions (Ekko,Diana,Ranger Rick,Yasuo), and I have seen many costumes based off them called "cosplays" (duh you guys know what it is). I have really wanted to create a cosplay, or at least a sword, or spear, or axe, or sword-spear-like-magic-weird-axe thing (don't worry, I didn't forget you ) but, i don't know where to start. I've seen some videos, but I can use more background than that. Please try to help me with some steps? :)

-eclipsekyd