As you reach the end of your PhD years, you may be invited as a reviewer for scientific journals for the first time. If you have never been asked to review a paper, and feel ready to take on the task, you can follow the recommendations of Dr. Cheplygina. Once you are invited to write the review, you can follow the procedure that I recommend for writing a review of a paper.
But what do you do after you have finished reviewing a paper? How can you keep track of your efforts as a reviewer?
The first thing you can do, is list on your full curriculum vitae which journals you are reviewing for. You can add this information in the section with your service appointments. But then again, there are a few drawbacks to this approach. First of all, by simply listing the journals, somebody reviewing your CV may not know if you reviewed one paper ever for the journal you mentioned, or if you review one paper monthly for this journal. Some journals send you a certificate with the number of papers you reviewed for them in the last year as a token of their appreciation, but for many journals it may even be difficult to prove that you review for them. And since nowadays in some cases you need to be able to provide proof of every single element on your CV, you may need a good system to confirm that you reviewed for a certain journal, and to keep track of the journals you review for and the number of papers you reviewed for them.
Publons is a service you can use to get an overview of your service efforts as a reviewer. Here's a list of a few cool features of Publons:
Publons is part of the Clarivate analytics empire, so they use Publons data for further processing. One of the cool outcomes of this data analysis is "Your year in peer review", the Clarivate list of highly cited researchers, and the Publons Hall of fame for "productive" reviewers.
Here are some examples of what you can do with Publons: