There's really no secret to how you should fold your hammock. The most important thing is to avoid wrinkles or folds in the fabric as best as possible. If the fabric is stored with too many wrinkles for a long time, those folds could become damaged. Stuffing it back into its storage bag is likely to lead to many small folds and creases, so that is probably best avoided. Laying it flat and folding it as you would a bed sheet makes for a tidy package, and it'll be much easier to get back into its bag.