[Help] I am a new cosplayer looking for help!

So I am wanting to do a cosplay of either Hisoka or Karupika from Hunter x Hunter, and I really need some help. This would be my first ever cosplay. If you are at all willing to give me some advice, wisdom, or ideas please lmk! Oh, I am only 15 so money is a key part- I have a summer job, so I don't have a lot of money right now.