"Sé cómo nadar." Almost every English speaker says it, and it sounds a little off to a native ear. The "how" is already inside saber. Saber plus an infinitive means knowing how to do something, so adding cómo says it twice. Sé nadar. I know how to swim. Same with sé conducir, sé cocinar, no sé bailar. Cómo only comes back when you mean the method, not the ability: sé cómo se hace, I know how it's done.