Maybe it's about time for your summer vacation. You've scored screaming deals on a flight and hotel thanks to Clark's tips on the radio and TV. (And, of course, because you're willing to follow the #1 rule of cheap travel, just like the man himself!) Now, all you have to do is throw some clothes in your suitcase and you're off to the airport!

Not so fast.

Packing for your trip is too important to put off until the day before you leave. If you're rushing around, you’re more likely to forget things, which could cost you a lot of money if you need to replace those items on your trip.

Here are 18 things you don't want to forget on your packing list for vacation:

1. Umbrella – Don’t get caught in the rain. Even if the forecast looks nice, you never know when there will be a pop-up shower or thunderstorm.

2. Phone charger - The good news is that you'll be able to find a replacement phone charger at the airport. That’s no problem. The bad news is that it'll cost you $20 or more.

3. Laptop power cord – A must-have item if you’re bringing your computer along for the trip.

4. Prescriptions – Bring enough medication for your entire stay (plus a day or two) to avoid wasting time and money getting prescriptions refilled.

5. Sunglasses - You probably won't have trouble finding a new pair of sunglasses, but you may be paying a tourist trap price for them.

6. Sunscreen - If there's room in your bag, take sunscreen along with you. You'll find it's more expensive at most beach destinations. Here's a look at the best sunscreen for your money.

7. Long-sleeved shirt – Have you ever had goose bumps during the summer because a place has the air conditioning on full blast? That’s why I pack a long-sleeved shirt just in case.

8. Bathing suit - A swimsuit is so easy to forget, even if you've spent months trying to fit back into it.

9. Belt - You might decide to skip a belt at the airport in order to breeze through security, but remember to pack one in your suitcase.

10. Personal hygiene products - One time I was stuck paying $3.99 for a trial size of mousse. Avoid resort prices at all costs.

11.  Bandages - It's better to be safe than sorry.

12. Passport or driver’s license - Don't risk missing your flight because you have to run back home and grab your identification.

13. Reading materials - There are plenty of books and magazines at the airport, but consider borrowing something from your local library for free.

14. Painkiller - You never know when a headache will come on.

15. Hand sanitizer - You'll feel a lot better about the coughing and sneezing passengers on the plane if you take this with you.

16. Wine - Carefully pack a bottle or two in your checked luggage to save a few bucks. Take a look at 5 must-try wines under $15.

17. Cash – You can avoid possible ATM fees at your destination by withdrawing enough cash before you skip town.

18. Snacks – Stash some snacks in your carry-on so you don’t get overcharged at the airport.

Of course, this isn’t a comprehensive list. It is, however, a good reminder to make a packing list for vacation before you travel. No one wants to spend the beginning of their summer vacation shopping for things they already have at home. Being organized ahead of time is the first step to having a great stay. So, make that packing list, check it twice, and enjoy your trip!

What items have you forgotten to pack? Add to this list by leaving a comment below.

About the author: Michael Timmermann paid off his mortgage in two years when he was 27. Now, he shares his money-saving tips on his blog, Save on Almost Everything.