For this, first of all, carefully examine the image of your hero. Consider the elements and details of his clothes and try to find something similar in my closet. Perhaps you have a skirt or a shirt similar to the clothes of your character, which will be easy to alter.
If you cannot find anything suitable, go to the fabric store with a sketch of the costumeand pick up the right materials.
Then make patterns. You can download them on the Internet, and you can do yourself. To do this, take the measurements and on paper draw a representation of the details of the suitand the right size.
Cut paper blanks, check them, applying to ourselves. If the items are vaguely reminiscent of the future costume, feel free to bring them onto the fabric, adding a quarter-inch around the edges for seams. Don't forget that the bend line on the fabric should appear on the mirror.
Next, you need to sew the items received from the inside. The more gently you treat the seams, the better and more durable will your suit.
You have to sew distinctive details to your hero costumehave, if any. Try exactly copy buttons, pockets, appliques, etc.
Now, when the costume is ready, take care of other elements of appearance of your character. Perhaps its special feature is the presence of the sword or just the clips you need to make them, too, that the resemblance was complete.