Set the league so the green links open the right Trade2 search.
Read the question under Walk the tree. Click a green link, look at the cheapest listing, then answer yes or no.
Type the three prices above before you spend anything. Continue only when the sale is higher than the cost.
Yes means do the next step. No means stop.
If it already has the mods buyers search for, list it. If it is a magic item with two of those mods and an open affix, it can enter the batch. A blank rare is a vendor.
Hard stop: Never omen-spam a dead rare hoping it becomes a mirror.
Early in a session the gold vendor or the Currency Exchange is sometimes cheaper than trade for one stackable currency. The profit is that gap. It closes the hour other people stand in it.
The finished item is only worth more than the materials on the day you check. A magic item that already has two useful mods is the start. A white base you Transmute is a different, usually losing, craft.
Once the two-mod batch is too small for the bankroll, the product is a base that already has the expensive mod locked. You buy that fracture from someone else. Fracturing it yourself is a separate bet, and it loses when the orb divided by the hit chance costs more than the spread.