Get a single +1/1 counter
If multiple flags appear, treat the card as high risk
Now comes the difficult part: between Carmen and Clavileno I actually think Carmen has a much higher power ceiling, but to reach that ceiling you'd need to start moving away from Vampires and into more efficient sacrifice triggers (Pitiless Plunderer) and lifegain payoffs (Archangel of Thune)
You'll want to keep him as safe as possible with Bodyguards, Locations, and characters that grant him Ward or Evasive because if your opponent can't get rid of him quickly, you can run away with the game.
Reprints focus on format staples, legendary creatures, mana rocks, and multiplayer-specific cards that rarely see Standard printings
As you are already so heavy on one drops you are an incredibly colour intense deck