How can I improve my portfolio?
My two cents
There are several things you can do to improve your Service Design portfolio:
Ask someone who has hired designers in the past to review it.
Watch or read public portfolio reviews.
Look at the portfolios of other service designers to get inspiration.
Sites where you can ask for portfolio reviews
Below you'll find websites where you can send your portfolio and get back a critique of your portfolio (in no particular order). These websites focus on UX portfolios but the feedback can still be helpful.
Marie Shaw (99$)
Ian Fenn (99$)
UXplaybook (99$)
Scott La Counte ($70)
The Designer Toolbox (99$)
Public portfolio reviews
I have added for you a few public portfolio reviews. These reviews are of UX portfolios, but there are still lessons to learn.
More Service Design questions and answers like this one
Check out all the questions about all the details on how to build a Service Design portfolio here.