apart the usual reccomendations for a pure system (reading an applying
UPGRADE.TXT and
CHANGES_AND_HINTS.TXT), the only other thing you should need is to update you multilib packages at the end of the upgrade process with the ones in the
13.37 folder (*-compat32 packages included: be aware that considerations in point 4 of the UPGRADE.TXT about removed packages apply also there): nothing else.