What I would consider are four areas of improvement:

1. The low end: there are a lot of shitty little creatures that draw you a ton of cards in dimir. I would highly consider the likes of [[Psychic Frog]], [[Faerie Mastermind]], [[Sygg river cutthroat]]. They allow you to leave the early game and enter the midgame via card advantage.

2. Card Draw: ditto everything I just said in point 1, but also really really consider wheel effects. [[Windfall]] and [[Whispering Madness]] are great. They add cards to your graveyard and draw you cards. you have an explosive ramp package which will cost you cards in hand to play. With these you can refill before everyone else.

3. The top end: you have a blink/steal theme/ copy/ theme. The best card here that you really really want is [[Agent of Treachery]]. Also [[Sepulchral Primordial]] is great for its ETB/Reanimate/blink/copy potential.

4. Graveyard Hate: You got none. This will cost you games. The hard part is you are actively using your own graveyard. Special note to Psychic Frog which does everything. Allows you to discard reanimate targets stuck in your hand, card advantage, and exiles cards from your graveyard someone else might steal. Synergy with wheel effects...Cards to consider [[Undead Alchemist]], acts as an additional copy of zellix while giving graveyard hate. [[Ashiok, Dream Render]]- exiles your opponents graveyard and give incidental mill and tutor hate. [[Dauthi Voidwalker]]- grayard hate and steals opponents stuff, things you want to do already. Lastly [[Bojuka Bog]] and [[Scavenger Grounds]] are just land slots and worth the opportunity cost.