A portfolio is like a special album that shows off your very best work. It's a collection of things you've made or done. People create portfolios to showcase what they're really good at and to show others what amazing things they can do.
To create an effective UX design portfolio, focus on key elements:
I found this article very useful to read its from Martijn van den Broeck who is currently a designer at Google Chrome.
Here are some tips:
Be personal: Tell your life story, what interests you and who you are. It makes you stand out from the crowd.
Share your viewpoint: The key to an effective viewpoint is that you don’t write what you think others want to read. Write what you want to write. If you write from your heart, you cannot go wrong on what you say.
Show your Process: You are doing a great job if you allow people to really get into your mind. Any design process is complex and hard to manage. So don’t pretend that it was easy if it wasn’t. It is perfectly fine to show your struggle. Why? How you deal with struggle reveals more of your personality than how you deal with success.