Even the smartest, most on-top-of-things couple can make mistakes during wedding planning. Here are the 10 things you should keep an eye on before saying I do.

1. Blowing off your budget.
It costs a lot of money to throw a wedding. Excited brides start booking vendors and making purchases without having a real budget and then are shocked to discover they've already spent all of their money (or parents' money) and don't yet have half the things they need. If you bounce checks or don't have the money to pay your deposits or make your final payments on the wedding day, your wedding will not happen. Trust us -- the band is not going to play all night if you don't pay. Planning a wedding is serious business. Make a budget and keep track of your expenditures so you won't be walking naked down the aisle.  

2. Messing up the marriage license.
There are so many rules surrounding marriage licenses that brides are always botching up this one. For instance, if you get your license 61 days before your wedding in Pennsylvania, you won't be able to legally marry on your wedding day because a license is valid there for only 60 days. Go to obtain your license the day before your wedding, and you may not get it in time because some states have a three-day waiting period. A common mess-up for those marrying for a second time is not bringing official divorce papers when you go to get the certificate.

3. Ordering your wedding gown too late.
If your heart is set on a couture gown, be sure to order by the six-month mark since your dress will be custom-made and, many times, made overseas. In addition, most off-the-rack dresses will require alterations, so make certain that you have enough time to get the gown fitted properly. You'll want to leave plenty of time for shipping and for your fittings. The same goes for the bridesmaid dresses.

4. Booking hotel rooms too late.
Brides often leave blocking out hotel rooms for out-of-town guests until the last minute. If you're marrying during a busy time and you don't investigate hotel availability in advance, you can end up with literally not a single room for your guests to stay. Your wedding will go on -- but no one will be able attend. Reserve rooms as early as possible. Begin your research up to year in advance, and make sure your block is booked at the eight-month mark. Be sure to include hotel information in your save-the-date cards or invitations. This doesn't mean you will have to pay for the rooms, you are just setting them aside -- your guests can put down their credit cards when they call to book their rooms.

5. Inviting too many guests.
Make sure your guest list and your reception site capacity match up numbers-wise. You can't invite 400 people assuming only 250 will accept, because if you end up with 300 acceptances, you may have to turn 50 guests away at the door. Most reception sites can't just add 10 more tables -- fire laws limit the maximum number of people allowed in any room at one time. Analyze your guest list from the get-go, assume 80% will respond yes, and limit your guest list accordingly.

6. Partaking in last-minute beauty treatments and crash diets.
Many brides think that scheduling a facial the day before the wedding will leave their skin looking angelic on their big days. Thinking of tanning the day before your wedding? Think again: you may end up with blisters instead of sun-kissed skin. Last-minute beauty treatments can lead to breakouts, mistakes or, even worse, serious infections. Same goes for crash dieting in the weeks leading up to the wedding -- after all those gown fittings, your dress may not fit! Stick to a long-term beauty regimen with lots of rest, a good diet, and safe over-the-counter beauty products like sunless tanners. Save the heavy-duty beauty treatments for at least two weeks before the big day or you could risk ruining all the hard work you've done to make your wedding -- and your photos -- perfect (never mind putting your health and happiness at risk for the most important day of your life)!

7. Underpaying invitation postage.
You'd be surprised how many brides just stick a regular stamp on their invites and drop the whole batch into a mailbox. All but a few wedding invitations require additional postage -- sometimes up to .55 cents. The postal service will not take pity on you -- your invites will be returned, rubber-stamped with that ugly "insufficient postage" sign, and it will take at least three weeks (never mind the additional $$) to get those invitations back out the door. Get one invitation weighed -- at the post office -- before purchasing your stamps. Note: square invitations require additional postage not only because of the weight but the shape -- so don't try to figure this out by yourself.

8. Ignoring religious restrictions.
Inappropriate attire for the church or temple, or skipping the pre-canae, may keep your officiant from marrying you when the big day comes around. Take your religious restrictions seriously. To avoid any day-of disasters, be sure to meet with your officiant within one month of getting engaged. Your house of worship may perform ceremonies only on specific days, so settle on a date with your clergyman before you start to book vendors and put down deposits. Be sure to ask him or her about religious rules, such as: Do you need to complete a pre-cana course? Can you write your own vows? Do you need to cover your shoulders? Is secular music permitted?

9. Trying to go it alone.
If you are a bride lucky enough to have been offered help by friends or family members, by all means take it! Too many brides try to do it all -- and this isn't a good idea. Delegate and use all the resources that are available to you When people offer to assist -- like your mom, your future mother-in-law, or your best friend -- find something for them to do, like researching a vendor or addressing invitations. On that note, it's important to keep in mind that these volunteers are not hired help -- be sure that you accept their contributions graciously.

10. Forgetting to focus on what's important.
Keep in mind that you are getting married and starting a life together, not just planning a wedding. Brides, be good to your grooms. And grooms, be good to your brides! Some tension between the two of you (and among members of your family) is inevitable due to the sticky topics that weddings stir up, but don't ever let things get out of control. Remember why you decided to take this leap in the first place!