DR of Denmark have today published the rules for DMGP 2013. Songs can be entered from now up until the 24th of September, as normal songs may not be performed or released publicly before the 1st of September. If you are not from Denmark you must collaborate with a Danish person on the lyrics or composition.
As normal DR will choose 6 songs to go straight to the final and an additional 3 or four songs will be chosen as wildcard entries. The date or venue of the 2013 DMGP has not been announced. Full rules are here.