Evil Mode best practice?

I’ve been using Vim as my primary editor for years and tried Emacs several times during that time. Then I discovered Evil and decided that it meets my demand for speedy movement well enough that I can …

Make emacs run in console mode (-nw) by default

I’m running Ubuntu 10.10. How can I make emacs run in terminal/console mode by default, as if I’d used “-nw”? And once that’s done, how do I force it to run in GUI mode (once) if I need to?