I've mentioned several times in the past what a big fan I am of Christopher Denise's work. I don't know if you know but besides making beautiful books he also blogs.
He recently posted about portfolios and what it takes to have a critical eye when it come to your own work. Updating and editing portfolio pieces and leaving only your best work is no easy task. He starts by saying less is in fact more and he found a solution on how to pick the best pieces. Click here if you want to know more.