Identify your goal: silky thickening (sauces/gravy) or tender baking (crumb/structure).
Choose the closest substitute from the table (start with cornstarch/potato starch for thickening, cake/AP for baking).
Measure using the ratio in the table; for sauce thickening, whisk the substitute into a cold slurry first if you’re seeing lumps.
Adjust cook time: starches thicken quickly once heated, while flours need a longer simmer to lose raw taste and fully hydrate.
Taste and adjust consistency at the end—add a splash of liquid for looseness or extra thickener (small increments) for body.