With only a few dozen games played, my early takes might be a bit off, but that's the thrill of new games, right
Whenever Xyris deals combat damage to a player, you and that player each draw that many cards
Very potent with Eternal Witness, Mystic Snake and even Spellstutter Sprite for an easy soft lock on your opponent
Well, some things that may draw you into specific colors are: A really strong rare you're excited about playing Having plenty of "removal"cards that can destroy, exile, or keep an opponent's card tapped Opening many cards in that color A good "mana curve" in that colorcreatures of different mana values, more on the 2, 3, or 4 end than on the 5 or greater end Several multicolor cards in those colorscards that have multiple colors are often more powerful than those with just one color Ideally, the colors you pick will have all four of those features, but if only two or three of those are true, that's plenty good