As the perfect party host, your hat trick is to make your soiree seem fun and effortless while hiding all the heavy lifting that went on behind the scenes. Jaime Geffen, the co-founder of YourBASH! event planning in Santa Monica, California, has put together everything from weddings, birthday parties and baby showers to movie premieres and product launches. Here, she offers some party planning tips for the novice and advanced entertainer.