Find a famous open-source project that interests you and that is open to contributions. There are webapps to help you do this. Contribute to the project, start

Find a famous open-source project that interests you and that is open to contributions. There are webapps to help you do this. Contribute to the project, starting with simple bug-fixes. They will be glad to have your help. You can then say, honestly, that you contributed code to that famous project, which puts you far beyond most candidates.