Stay on the beach. You can get hotels elsewhere, but why bother? Look for a nice loft or house on the beach on Craigslist for cheaper than most hotels.
Avoid driving. Traffic is crazy on the beach in Miami during Memorial Day weekend. Walk or cab it. It will be a lot more fun and less stressful that way.
Party at the free spots during Memorial Day weekend. Wet Willies and Fat Tuesdays are both located on the beach and don't have a cover charge. Also, a lot of people gather friends together, bring a radio and grab some drinks to have their own party right on the beach.
Make reservations at local hot spots if you're looking to party with the money crowd. Flyers are handed out all weekend to the hottest events, so grab a flyer and reserve a table at the club of choice.
Socialize and make some new friends. Everyone is in a party mood Memorial Day weekend in Miami. Take the time to meet people, and you're bound to be invited to plenty of parties so you can hang out and have a really good time.
