I am not now, nor have I ever been engaged.
But I will be! Someday! And when I acquire such a status, I will be fully prepared for the daunting and exciting task at hand.
A few months ago, a friend of mine, who is actually getting married, showed me her "Wedding Inspiration Board." The purpose of this mosaic of pictures from magazines and websites is to show the overall mood and motif of the ceremony and reception. One might include swatches from bridesmaid dresses, examples of bouquets or boutonnieres and cake photos. Here are some examples I found from one of my favorite wedding blogs, http://snippetandink.blogspot.com/:
I would highly recommend making your own Inspiration Board from your collection of ideas and giving copies to all of your vendors so that everyone is on the same page (no pun intended). Now, if you find that your inspiration board is starting to look like a billboard... you might want to cut back on the clippings. The Inspiration Board should serve as a reference, not the Encyclopedia Britannica of your wedding.
Board contruction should be fairly stress-free and fun. Put on a movie, make some popcorn (the less butter the better, as to keep from grease-printing your pictures) and enjoy!