Preparation

make sure a clean build works
Check whether all significant changes are in CHANGELOG
List of contributors git log --format="* %aN <%aE>" vLASTRELEASE..HEAD | sort -u > /tmp/authors.txt
Check for ABI / API break, determine Version (MAJOR.MINOR.ABI.PATCH)
Change [unreleased] to [MAJOR.MINOR.ABI.PATCH] in CHANGELOG
Update version in CMakeList
Commit with message: `git commit -m "Release MAJOR.MINOR.ABI.PATCH" CMakeLists.txt CHANGELOG.md
prepare release statement / tag annotation file: copy last Tag's annotation format (basically, contributors top, new Changelog bottom

Tagging

git tag --annotate --sign -F /path/to/release_statement.md vMAJOR.MINOR.ABI.PATCH
git push yourrepo vMAJOR.MINOR.ABI.PATCH && hub pull-request -b {master|maint-MAJOR.MINOR}
let CI do its thing; if that's OK:
git push origin {master|maint-MAJOR.MINOR} vMAJOR.MINOR.ABI.PATCH
on github, mark release