Cooking is very important skill, since you can make raw fish edible, which could save you in battle.
To start cooking, use your Raw Shrimps from fishing on the Range (the stove) in the house next to the Catherby bank. After you've cooked them, bank them and repeat the earlier step. Do this until you reach level 40.
Gather a decent amount of Raw Tuna and cook them on the Range. Raw Tuna give better experience than Raw Shrimp. Cook tuna until you reach level 60.
NOTE : Drop any burnt food, because you won't be needing them.
Now you should be able to cook Raw Monkfish. Monkfish give even better experience! Cook Monkfish until level 75.
NOTE : The higher required level for food to cook, the more health they will restore when you eat them.
At level 75, you should be able to cook Raw Shark. This type of food gives generous amounts of experience. Cook Sharks until level 80.
Lastly, you can start cooking Raw Manta Ray. Manta Ray give the best cooking experience and health when eaten. Cook these until you receive the max level, 99.
NOTE : It is highly recommended to continue fishing for food, such as Sharks or Manta Rays, because they are often used while fighting in battles.
When you master the Cooking skill, you can buy the Cooking Skillcape to show that you're proud!
Guide Created by Evan.
Editing, Organizing, and Pictures by Cali.
Thanks Aaron for helping me with research!