Select a genre
You should know the genre before putting all the pieces together. If you are applying for a job then make sure that you are making the portfolio according to their requirements. Mostly, they ask you to send samples of your work which falls into a specific category. However, there is also possibility that they will demand samples of different genres. You should dispatch a portfolio that can prove you a versatile designer.
Take images of your designs
You must take photos of your designs and attach them with the portfolio. These images will help the other party to see how your designs look in reality. Make sure that your photos are clear and large enough to cover all the details of your designs otherwise there will no sense in attaching images with your portfolio.
Include samples of fabric
To give an idea to your potential employer, you should include fabric swatches as these samples will help them in checking the texture, feel, dimension etc.
Give brief description
You must label everything and give brief description of each design. If the design has been used earlier then do mention the event. You should also give information about the character who wore this outfit. You must put all the information wisely.
For example, if multiple designs were used in one function then arrange them together. However, make sure that one page does not contain more than two designs otherwise it will be a mess.
Follow a theme
You can follow a theme while making a costume design portfolio. Remember, you need to show your best work but you also need to prove your versatility.