To fold an 'X' shape with aluminum foil for cooking, follow these steps: Start with a large piece of aluminum foil. Fold it in half lengthwise to create a crease down the middle. Then, fold each of the two halves diagonally towards the center, creating two triangular flaps that meet at the center. Repeat this process on the other side, folding the remaining halves diagonally towards the center. The result should be a cross shape with four triangular flaps that intersect in the middle. Ensure the foil is secure and evenly folded to prevent any food leakage or foil tearing during cooking.