Buy recyclable materials
Buy beverages in aluminum cans and glass bottles that can be recycled or pick up soda and other drinks in larger sizes to pour individual servings from. By buying wisely, you can make a huge impact. Glass and aluminum can be recycled into more glass bottles and aluminum cans, and the process never degrades the quality of the material. It can be reused over and over again. Plastic is tougher to recycle, and the process of recycling breaks down the chemical structure of the plastic each time it's recycled, weakening the material. Plastic has a limited number of reuses.
Keep the food local and organic
Shop at your farmer's market for fresh produce and select organic wines and beers.
Think multi-purpose and repurpose
Look for things around your home that are reusable. For example, use glass jugs as wine decanters at one get-together, then use the same jug as a flower vase at another. Or, use your party decorations as gifts for the guests.
Also, take a look at things around your home from a different perspective. You know those old paint chip cards you used when you were trying to decide what color to paint the spare bedroom. They can be turned into great gift tags or wineglass IDs. Put a hole in them with a hole puncher, string ribbon through them and tie them to your glass or package. And, of course, don't forget to stock up on the organic and biodynamic wine.
BYOSP (bring your own serving pieces)
If you hire a caterer, bring your own serving dishes to him before the party. That way, the caterer can place prepared food in your serving dishes. You'll eliminate the need for the Styrofoam or plastic trays used to transport the food to your party, which is just packaging that will end up in a landfill.
Also, instead of plastic wrap to cover items, ask the caterer to use wax paper and aluminum foil. Wax paper is completely biodegradable. And, aluminum foil is recyclable as long as the food isn't baked or stuck on the foil.
Rentals
You can rent decorations and dinnerware. Return them when you're done, instead of throwing them out. This can be one of the simplest green things that can be done for entertaining...and most affordable.
Recycled, if you please
If the guest list is so long you must use disposable dishes, look for biodegradable choices such as bowls and dishes made from recycled paper or a renewable resource like bamboo. Also, if you must have balloons, use ones made from recycled latex.
Skip paper and plastic dinnerware
It's better to use your own dinnerware, serving pieces, utensils and glassware — and throw them in the dishwasher. Invest in a good inexpensive set of stainless eating utensils that can be used over and over again.