Find a loose leaf notebook to keep all of your lists and information that you gather. You should also have a three-hole punch, and a set of pocket folders for things that you can't punch and put in your binder. (You can use a folder, a spiral binder, or a box but they're not as easy to keep organized.)
Keep a page in your notebook for a list of itemized expenses, including both anticipated expenses and items already paid.
Decide on a budget. How much will you spend for your event? Will anyone else be sharing in the cost? Develop your budget, deciding how much you will spend for each item or service.
Make sure you have extras and backups.
Anticipate potential problems before they develop. You can often avoid or lessen the effect of any problems or emergencies that occur by anticipating them beforehand and taking steps to see that they do not spoil your event.. What are the ways that any emergencies will be handled? What are your contingency plans for each major element of your event? What would you do if....?