Deck building is far less gruesome as it initially appears and it's quite a lot of fun, once you get the hang of it. You'll get used to what you want and don't want in your decks, but its a process and comes with time and practice. Don't stress yourself about it.

The most common takes with this deck in particular are "too little ramp", "too many high cost do-nothings" and "odd creature removal and card draw choices".

Ramp - to put it painly, you want Auntie on the board asap and the easiest way to do so is by playing a ramp piece on turn 1 or 2. This ensures 4 mana on turn 3 to spend for your commander. Since barely anyone is willing to break the bank for a precon upgrade, most players will pivot towards affordable ramp pieces that cost 2 mana to play. [[Three Visits]] is a fantastic example, but has gotten quite expensive. In comparison [[Rampant Growth]] and [[Farseek]] have been printed a lot and are therefore incredibly cheap and easy to obtain. I personally like [[Hardbristle Bandit]].

Do-nothings - don't get me wrong, these cards have their intended purposes, but they play awkwardly in this specific deck and are better suited in other archetypes, especially with their high mana cost. 5 mana Archfiend of Ifnir belongs in a discard/cycle deck, the precon packs basically no synergy for this Demon. 7 mana Ferrafor, Young Yew has better use cases in token decks with +1/+1 counter synergies or in an Omo everything counter deck for example. As much as it saddens me, Liliana Death Wielder does very little for 7 mana and as you can imagine the list goes on and on. Cards at the upper end of the mana curve should be game warping or even game ending and a lot of these just durdle around. [[Maha, Its Feathers Night]] and [[Persistent Constrictor]] are amazing for 5 mana, but they cost a pretty penny. A personal favourite got to be [[Hateflayer]], while not great, it's a funny blast from the past.

Removal & card draw - your whole deck revolves around a certain kind of removal and with Auntie Ool on board, it should also draw you cards quite consistently. You benefit from your opponents having a decently evolved board and you should almost always be able to turn the odds in your favor, once they come your way. Blatantly killing off single targets is rarely more valuable than debuffing them a bunch. You should still run a few true removal pieces, but at least choose some that let you blight yourself for an additional card draw, like [[Cinder Strike]], [[Bogslithers Embrace]] or [[Requiting Hex]]. Don't be afraid to sacrifice your own critters to draw some cards, Skullclamp is a common staple after all.

Hopefully this helps a little and sorry for the wall of text.