The first thing to decide on, in planning your wedding, is how much to spend.
Are either of your parents paying for it? Are you? The average wedding today costs between $20-$30K, but there are plenty of ways to do it for less, if you are so motivated and have a limited budget. Be realistic about your incomes. And, above all else, avoid debt. There is no reason to put $25,000 on a credit card for a one-day shindig that could take 10 or more years to pay off.
Come to an agreement on how much to spend. Both of you have a vote in this process--men, pay attention at this point, because the decisions you make now will affect you for years to come.