My 16th Birthday Ideas?

You could start out by giving out a Lei to each of your party guests as they arrive. Make sure to have tropical/island music playing. Make a pineapple/banana punch. I've made one many times for baby/bridal showers and everybody loves it. You can Google "banana punch recipe" and choose the one that uses pineapple juice in the recipe and that you have to freeze. Have little umbrellas to put in the drinks. Use a tropical floral invitation and use paper plates/napkins that match the invitations. Make sure your food is tropical inspired. Like I said, you can Google food ideas and get lots of good recipes. Have fun!