Before you start with this, make sure you understand the release model all developers should follow for core components.

Stable releases are created from the stable branch of the repository. So before you start make sure you are working in this branch.

# get the stable branch
git checkout --track -b xfce-4.10 remotes/origin/xfce-4.10

# pull the latest changes
git pull --rebase

Now make sure all the bug fixes are committed and pushed to the remote repository. You can check this at git.xfce.org as well.

For the version number the micro version is increased by 1. So 4.10.2 becomes 4.10.3.

Unstable releases are created from the master branch, which is in this period in feature-freeze. There we use an odd minor number. So the first development release is for example 4.11.0, then 4.11.1 etc.