For Gore-Tex clothing, there are, for example, special repair kits. The patches are mostly standardised sizes and shapes (round and square), therefore they do not need to be cut to size - they can be used directly.
Applying the patches requires no great skill: Ensure beforehand that the damaged area is dry and free of dirt or other foreign substances, otherwise the patches will not adhere. Pull the material taut and press the patch over the damaged area for a few minutes. If you have patched the hole on the go, you should then iron it at home to ensure it holds well. Alternatively, if you are on the go, you can heat a pan with water and then - just like an iron, use the hot surface to press down on the hole to accelerate the drying process.
An alternative to patches are adhesives such as Seam Grip. These adhesives hold for longer than patches, but require longer to dry. For most products, the functional garment should be left to dry for around 24 hours. That’s why adhesives are suitable as quick fixes. The advantage of adhesives, however, is that you can use them to secure loose stitching - which you cannot do with patches.