Make sure nothing is bent, cracked or otherwise broken. When assembling, make sure the z gantry is square - put the screws in loosely and slowly tighten them evenly, then before making them tight, make sure it’s square. Best bet for a beginner FDM machine is going to be a basic PLA.
I’ve heard nothing but good things about these, if I didn’t have a Bambu I’d definitely look into getting one