Decide whether your use is no-heat (smoothies, dressings) or heat/baking (sautéing, roasting, baked goods).
Choose the substitute that matches your goal: closest mouthfeel (fractionated coconut oil) or minimal flavor + heat stability (avocado or extra-light olive oil).
Use the ratio 1:1 by weight for most recipes; if your substitute is solid at room temp (refined coconut oil), melt first and cool slightly before mixing.
For baking, mix the oil fully into wet ingredients to prevent grainy texture from cooling fats.
Taste-check after mixing: add a balancing flavor (a pinch of salt or a small amount of vanilla/citrus) if the substitute tastes more assertive than your original.