It's a fine line, really. Take one step over and you've entered Clownsville, don't take any steps at all and you're left with dull and sans texture or color.
A big wedding trend lately has been to create an overall matching scheme, yet without having everything matching. Get it? So how do you get it? With a few key points to always keep in mind, you can have an elegant, eclectic, gorgeous wedding fit for the magazines. Besides, let's just say that I personally like to mix and match just for the sake of surprises and personality.
1) Pick 2-3 colors or patterns MAX. Sometimes you can fudge this rule a little with a fourth, but only if the effect doesn't produce eye sore tendencies. Try a couple of solid colors and then choose a plaid patterned item that marries all the colors together. Or even several coordinating patterns work well, such as dots, stripes, and plaids.
2) Mix up the centerpieces. This can be mixing up the vases or containers (alternating high/low, 1/3 of the tables with candlesticks, others with vases and still others with candles, etc), or totally different floral arrangements. The key to the latter- keep some of the same flowers in each arrangement to create a matching effect without actually "matching".
3) Mix different textures- try paper & fabric, shiny glass or metal mixed with soft sheer items like chiffon, or natural element mixtures like fruit and moss.
By choosing your 3-4 favorite textiles, patterns, or colors, and evenly distributing them throughout your party, the look with be cohesive and will still surprise your guests at every turn.
#1: EyeSpy Photography Via Style Me Pretty
#2: Amelia Lyon Photography via Inspired By This
#3: Carlie Statsky via Green Wedding Shoes