I posed this question a few days ago as a comment and was encouraged to make it into a standalone post. I'm asking it specifically within the context of Commander, but suggesting your workflows for other formats would probably be helpful for people who aren't me :P

As someone who has been casually playing MTG for several years, I'm only now starting to try to build my own EDH decks from scratch (as opposed to just buying and tweaking precons). I've tried to do my due diligence and research important topics like ramping & mana bases, read articles & posts about determining wincons & threats, and have scoured through EDHREC and Skryfall for thematic/synergistic cards... And all of that is great for finding cards that *could * work in a deck.

But this is the part that most articles & instructional pieces stop at (or glaze over). So now I have a giant pile of theoretical cards for a theoretical deck, and no idea which ones I should actually purchase or playtest with. There is no one-size-fits-all method for paring down your deck, so I'm hoping to hear how you, personally, go about doing it (and whether or not you've come across articles that address this part).

Currently I’m trying to use tags on Moxfield but it’s mostly a confusing mess as I try to trim down ~200 possibilities into a lean, functioning deck. Tags seem a bit too inflexible when I'm trying to tag by both function (ramp, threat, protection) and priority.

Big thanks to Mike, Andrew, gildedjake, and LovesTha BGU who have already chipped in some ideas at this comment. I'll leave it up to them whether or not to repost their comments here.