Conditional: entertains a case as provisional, then states what follows once it holds; 就 marks the consequence and may drop.
字源 FORM what the parts do
假 is a person (亻) beside 叚, the old graph for two hands passing a thing on loan, what is taken provisionally rather than owned. 如 follows where the supposition leads. 就 opens the consequence and fires it once the case holds; with 假如 it can drop.
故事 STORY a scene to remember it by
A thing is taken on loan and set on the table, treated as one's own for a while; everything done next is built on top of it, though it was never truly bought.
自撰字源記憶法
框 · Frame
假如 [supposed case]（的話），（就）[consequence]
觸 · Trigger
You float a case you are not asserting as real and lay out what would follow if it held.
序 · The move
1State the supposed case after 假如; 的話 may close it.Is this entertained, not asserted? A case taken as already true wants 因為, not 假如.
2Open the consequence with 就 before its verb, after the subject if there is one.If you keep 就, does it sit after the subject and right before the verb? With 假如 you may also drop it.
3Confirm the register fits.Reads as written or considered? Swap to 如果 for the neutral everyday version, 要是 for the casual spoken one.