Identify how you’re using queso fresco: crumbling/topping vs mixing into baked layers vs adding creamy moisture.
Pick the closest texture match from the list (crumbly cheeses first for toppings; thinned cream cheese only for creamy mixes).
Swap using the ratio above; for very salty options (feta), start slightly under and adjust after tasting.
If your dish is hot and you want less melt, add the cheese at the end (or bake uncovered for the last 5 minutes).
Taste and correct: add salt only if the substitute is milder, or add a squeeze of lime for extra tang.