Cooking fish significantly improves the flavour; some fish such as salmon can be served raw and can taste fine. This does not apply to most fish and different methods of fish cooking will produce different results. The various methods will also determine the look of the fish. Fish can be prone to breaking up and flaking during cooking, although this is a good way to check that it is done in order for it to retain its shape there are a number of different methods that can be employed. As a general rule though, most fish is cooked for a very short period of time.
Obviously the type of fish cooking method that you choose will depend on your recipe, but one of the very best ways is to steam it. This will do nothing for flavour, however, so bear in mind that you will want to make sure that you season it before you begin the steaming process, even if it is very simply with salt, pepper and a small amount of oil. Extra virgin olive oil is ideal as it imparts its flavour into the fish. Wrap the fish in some foil with the seasoning and put in on a trivet in a saucepan so that it is not touching the water. Put a lid on to retain the steam and check it after 10 minutes to see if it is done, returning it for an extra few minutes if necessary.
Poaching can flavour the fish, and the liquid it is cooked in, but care must be taken as the fish will flake in the simmering liquid. If for example you are going to prepare a fish pie you will need to poach the fish in some milk so that the milk gains the flavour of the fish for you to make a béchamel sauce with. Fish cooking using this method is ideal when you are going to breaking the fish into pieces anyway, such as in a fish pie.
The most common method used when fish cooking is to grill it. Grilling works best as the heat from the flame is exposed to the fish, it is this colouring of the fish that gives it flavour. Care must be taken to ensure that it does not burn so you will need to keep an eye on it while it is cooking. If you are cooking some oily fish, such as mackerel then grilling is an ideal fish cooking method.
Depending on the fish that you are going to cook you could try frying it, as a fish cooking method this works really well as it imparts a lot of flavour into the fish. Use good quality oil and season the fish with salt and pepper, and perhaps some lemon, before you begin cooking.