If you want to see your decorations before purchasing a large quantity of them, some online retailers will send sample swatches of colors for fabric items or a small sample item. Check out a bridal expo, they usually come to larger cities a few times a year, so one may be near you.
Before you by every decoration you think you might need, find out what is included at the church, if they have their own decorations and especially your reception site. Some venues actually include centerpieces of silk flowers or candelabras in the price of the reception. Also determine a color scheme so you only get what you need and think about how it will look with the colors that are already in the room where your reception will be held.
For decorations that are really personal or unique try home goods stores or craft shows. Craft shows are a great opportunity to find artists with unique talents that you could showcase at your wedding, and might even be something that you can keep to decorate your home. Finally, think thematically, color, season, and personality. If your groom proposed to you somewhere special and you can bring some of that décor to your wedding, it would be a great, individualized touch.
Make a list of everything you need and the amount. You will probably have more pews to decorate than reception tables, so you want to be sure that you have enough of each decoration. If you are going to be making anything yourself, purchase a few extra supplies...just in case!
Source : http://ezinearticles.com/?Find-the-Best-Wedding-Decoration-Supplies!&id=2856568