Usually I am using the packages from the official repositories. However, sometimes it's necessary to use a newer version, I recently had to do this with strongswan and I'm sharing the procedure for other people to try.
Get the build dependencies
apt-get update
apt-get install devscripts fakeroot
apt-get build-dep strongswanObtain and build the package
mkdir ~/work
cd ~/work
debcheckout strongswan
cd strongswan
sed -e '/dh_strip/ s/^#*/#/' -i debian/rules
sed -e 's/debhelper.*/debhelper,/g' -i debian/control
dpkg-buildpackage -rfakeroot -uc -b
On Debian 8.7 Jessie (fresh install on a GCE, Google Compute Engine, VM) … I was unable to use `apt-get build-dep strongswan` as directed here. I ended with in a tangle with dh-systemd and debhelper dependencies which I finally had to use `aptitude` to resolve. Even then I need to try it twice, rejecting the first offered solution on the second attempt. Additionally I needed to add -d to the `dpkg-buildpackage` command.