Honestly, I would say that the first thing to do is take a realistic look at how much you think you can put toward the wedding. Then write a list of the most important things that you want for your wedding (whether it is a perfect dress, big cake, photography, whatever). Once you have decided what items you MUST have for your wedding, then begin forming a theme around it (either based on color, flower, symbol, etc.)

Also be sure to remember that while everyone wants a perfect wedding, but at the end of the day, it is just a day, so make sure that you don't jeopardize your life after the wedding (i.e. going into major debt, or fighting over silly little details).

Sorry I am getting a little preachy, just got through major vendor and budget issues.

Start thinking about the theme and stuff though, and I promise the preaching is over, got tons of ideas.