It is absolutely essential for a graphic designer to have their graphic design portfolio ready at all times. This portfolio showcases what you are capable of doing in line with your work. It shows your future boss or potential clients your edge and your style of work. And since more people are researching online, you might as well have an online portfolio as well. Just make sure to prepare a hard copy when you meet them in person. 
When you organize your portfolio, this is one of the quickest and best ways to demonstrate your unique designs, abilities and it reflects your experience in the field. You can also indicate your awards if there are any. Your future boss or future clients won’t be able to find out that your former work had employee rewards program or any strategic rewards, so tell them about it here.
There is simply no one particular design that fits all. People have different tastes and preferences which is why there is no single way of doing a design. Who is your market? This is what you should keep in mind when you start creating your portfolio. This will start shaping your ideas.
Your potential employers or customers are most likely within the design or graphic industry. Employers can also be designers themselves. If they are, it means that they know what they are looking for in a graphic design artist so they would most likely want to know the details of your portfolio.
Customers who are looking for a designer, on the other hand, is looking for the overall look of your designs so they can see if it fits their requirement. So you can be detailed with your work or you simply have a page that showcases the different designs. To be on the safe side, make a flexible or adaptable portfolio.