You can learn how to create Debian repositories with reprepro in the Packagecloud settings.
This how-to post explains the steps of building Debian packages for simple shell scripts.
This article talks about APT 1.2.10 backport for Ubuntu Trusty (14.04) and Ubuntu Precise (12.04).
In this article, you can find how APT Hash sum mismatch happens and how to resolve the problem.
This article explains how to inspect and extract Debian package contents with easy-to-follow sample commands.
To prepare Debian packages, you can use dh-make. Check this post to discover ways to prepare packages.
This post explains about building Debian packages with debuild commands. You can find sample codes and easy-to-follow guides.
This post explains about setting up and building Debian and Ubuntu packages with pbuilder.