In the life sciences, problems with identifiers impede the flow and integrity of information. This is especially challenging within “synthesis research” disciplines such as systems biology, translational medicine, and ecology. Implementation-driven initiatives such as ELIXIR, BD2K, and others have therefore been actively working to understand and address underlying problems with identifiers. Good, global-scale, persistent identifier design is harder than it appears, and is essential for data to be Findable, Accessible, Interoperable, and Reusable (Data FAIRport principles). Here, we build on emerging conventions and existing general recommendations and summarise the identifier characteristics most important to optimising the utility of life-science data. We propose actions to take in the identifier ‘green field’ and offer guidance for using real-world identifiers from diverse sources. ; Other ; ORCIDs corresponding to the authors are: http://orcid.org/0000-0002-9353-5498 http://orcid.org/0000-0003-4155-5910 http://orcid.org/0000-0002-2513-5396 http://orcid.org/0000-0002-1010-3121 http://orcid.org/0000-0003-4727-9435 http://orcid.org/0000-0002-9091-5938 http://orcid.org/0000-0003-3499-8262 http://orcid.org/0000-0001-9823-1621 http://orcid.org/0000-0002-3469-4923 http://orcid.org/0000-0001-9114-8737 http://orcid.org/0000-0001-8479-0262 http://orcid.org/0000-0001-6867-9425 http://orcid.org/0000-0001-6666-1520 http://orcid.org/0000-0001-5404-7670 http://orcid.org/0000-0002-0643-3144 http://orcid.org/0000-0002-2036-8350 http://orcid.org/0000-0002-4625-743X http://orcid.org/0000-0002-6309-7327 http://orcid.org/0000-0002-1615-2899 http://orcid.org/0000-0001-5454-2815 http://orcid.org/0000-0002-1611-6935 http://orcid.org/0000-0002-9533-5684 http://orcid.org/0000-0002-1034-5171 http://orcid.org/0000-0002-4980-3512 http://orcid.org/0000-0002-6601-2165 http://orcid.org/0000-0001-9853-5668 http://orcid.org/0000-0001-5306-5690 http://orcid.org/0000-0002-5595-689X http://orcid.org/0000-0002-0405-8854 http://orcid.org/0000-0003-4958-0184 http://orcid.org/0000-0001-7020-1236 http://orcid.org/0000-0001-8936-9143 http://orcid.org/0000-0003-3156-2105 http://orcid.org/0000-0002-1279-5133 http://orcid.org/0000-0003-1219-2137 http://orcid.org/0000-0003-3035-4195