The best should be first …

It makes sense to me … showing a portfolio is not like writing a novel where you start slow and build the momentum to get to to the exciting end. When someone reviews your portfolio, first impressions are critical, so perhaps consider to put the best at the start … or you risk loosing it.

[... ]I would also like to add that in my experience of showing photographer’s portfolios for over 20 years in the real world an art director generally makes up his mind on you and comes to a decision very quickly. So my best advice to get work is to go for it and shoot your wad in your first 8 images - if the client isn’t sold on you by then nothing you show subsequently is likely to shift that initial impression. If you save some of your best images for later in the book you are essentially wasting them. [via freelance switch].