If Mother Nature were an event planner, she'd tell you this: The best parties take place outdoors, where the weather is warm, the mood is relaxed and the décor is organic. Whether you're throwing a graduation barbecue, a romantic picnic or a birthday pool party, one thing's for certain about outdoor events: Elegance lies in simplicity. We grilled party planner extraordinaire Russell Lefebvre, who's organized dozens of parties as IMI's event planner, on hosting an awesome alfresco event. Thankfully, he told us everything under the sun-and stars. Here's his advice:

Pick a theme. It can be loose, like Mediterranean food or an Asian night, and still be sophisticated, Lefebvre says.

Know what your guests like. If there are vegetarians, for example, be sure to have meatless options. Know if an invited guest likes a certain type of scotch and try to have that on hand.

Make lists. "Organize, organize, organize," Lefebvre says. "It's tedious work, but it pays off." Do as much as you can in advance so you won't be panicking come crunch time.

Keep it simple. Especially when it comes to food. While you may want to make a few key dishes (that you've made at least once before-do not leave experimenting to party day!), Lefebvre recommends purchasing some things from a gourmet grocery store or your favorite restaurant. Personalize the store-bought dishes by displaying them on eye-catching platters with beautiful garnishes.

Don't go overboard with décor. Less is more, Lefebvre says. You already have nature on your side, so play up the lush trees, running water and beautiful sky. To add elegance, bring in flowers. One big bouquet of garden roses may be enough, or go with a few centerpieces, but be careful: "For the most part, men hate centerpieces," Lefebvre says. "You either want them short so people can talk over them, or skinny and above people's heads, branching out." Candles are stellar for adding a stylish element to a nighttime affair. "They can be freeform or running down the center of the table," he says. If it's more formal, opt for ornate brass or silver candelabra adorned with real flowers.

Consider live entertainment. There's a reason why most bands love to tour during the summer: When the weather is nice, people are happier, which makes them want to celebrate, which, in turn, makes them want to listen to live music. Place a few violinists near the champagne for a sophisticated touch; or, for a more laid-back affair, hire your favorite singer/songwriter.

Enjoy yourself. "The worst is when a host is frazzled," Lefebvre says. "Don't try to be a perfectionist and have the best food. A party is about the occasion. The host should be like a guest. If you burn the duck, you burn the duck."