Nothing special to the 337.. I have only a few hours in the 337 but over 700 in the 0-2A which we flew quite a bit heavier than the civilian version.
Anyway, start the rear engine first to make sure you don't forget to start it. Single engine performance is less than stellar.
As I remember, the hyd pump for the gear is on the front engine so if you lose the front engine on takeoff DO NOT ATTEMPT TO RAISE THE GEAR. The gear doors open down and form a cup which can easily cost you 5-7kts QUICKLY so make sure which engine has failed before grabbing knobs (a good rule regardless of the airplane).
Here is a fairly good review..
http://www.superskyrocket.com/pages/.../history_2.htm
A second read is here..
http://tinyurl.com/6fazcj
The aux fuel tanks are not to be used until you have burned about an hour of fuel out of the mains and DO NOT change both engines to the AUX tanks at the same time. Yes, I know the chances of it happening are rare but I can assure you, it is possible to run both tanks dry AT THE SAME TIME and pulling off after marking a target for a set of F-100s is NOT the time for both engines to quit. And yes, obviously they will restart when you switch back to main tanks.
Enjoy the Mixmaster... it is a comfortable cross country airplane.