Okay, this is definitely one of those "I'm sure everyone already does this but me!" tips....
I'm not a Times New Roman fan. My latest favorite font is Century Gothic. So, when I'd start a new document, the first thing I always did was start typing, select everything I just typed, and then change it to Century Gothic. Everything else I would type would then be the font I wanted.
But then I discovered that it is EXTREMELY easy to switch the default font in Word. Here's how:
1. From the "Format" menu, choose "Font"
2. Choose the font and size you want to be the default
3. Click the "Default..." button at the bottom of the window
4. You'll see a box confirming that you want this to be your default. Click "Yes"
...and that's it! Now, each new document will have this font as the default.