Generally 1 att = 2,5 mainstats so if you get +4att on an mchaos you already outdo a Superscroll +9 mainstats (equivalently 3.6att)
Most items have base att/matt and can be mchaosed for 2 to 3 times.
For 2 slots: Aim for 15+ attack and not too much minus on mainstats or some plus (i.e +15att +8 luk if you are a thief)
For 3 slots aim for 20+ attack and same thing.
Just super scroll after the good mchaos. Dont use cogs since cogs sometimes give +0 as its range is +(0 to 4) why gamble with cogs when super scroll gives+3.6att guaranteed.
For non att items base like sweet water monocle/tattoo:
Poor method: use gollux occult scroll +1 att base then repeat mchaos process like above. Or just super scroll all the way(recommended)
Rich: fail all of its slots to 0, then starforce it to 16*, css the slots back up and then mchaos, this method doesnt waste 1 slot on base gollux scroll but its a lot of hassle.