I don't know how active any Magic discussion is on here aside from thatpinguino's posts but I'll post up here anyway, you never know!

I'm relatively new to playing Magic, my friends got me into it through an intro deck league that a society at my uni was holding. My friends only really play one variant of the game which they interchangeably call commander and edh, they often have multiple decks for it with them so will let me play one of those with them. It's 100 cards full of dumb interactions, one-turn-kills and all-around shenanigans and I love it, so I'm wanting to get a deck of my own.

I want to build one with either Narset or Shu-Yun, two legendary creatures I got during the league that I fell in love with using. But I don't really know how to build a deck properly, I fumbled my way through building upon the intro deck with stuff that's in standard so to try and build a deck for Commander feels a lot like going immediately into the deep end. Is there any tips or help people can give me to build a commander deck, or a deck in general?