Are you using Windows?
Right-Click the dominions icon on your desk. Check the properties. I have mine set to do this...
"D:\Program Files\dominions3\dom3.exe" -fwacd --magicsites 75 --renaming --indepstr 7 --hofsize 15 --eventrarity 1
The fwacd does things like set it for windowed mode, no fades, no animated backgrounds, no credit screen at the end. I also set the magic sites to 75, renaming on, indepts to 7, half of fame to 15, and events common. You still get the screen on each game that lets you change those but at least it will come up with my preferences as a default.
You could also tell it what era and map to use each time if you really wanted to.
The entire list of command line switches is available here..
http://www.dom3minions.com/docs/CommandLine.txt