You've booked your flights and accommodation and got your spending money ready. That's the financial side of your vacation taken care of, right? Not necessarily. There are some hidden costs that can really bump up your holiday costs. Here's what to take note:

(Not so) cheap flights

Budget airlines often have incredibly cheap fares, but sometimes the prices really are too good to be true. Things like luggage charges may not be included in the price tag. You may also have to pay for 'optional extras' such as allocated seats, checking-in services and even in-flight entertainment. Read the small print to see what your 'bargain' actually covers. Cheap flights can also have inconveniences attached to them. For example, they will often run at unsocial times. Have you checked the set-up at your destination to confirm whether you can quickly and easily get to your accommodation? If you're landing in the middle of the night, your only option may be an expensive taxi ride. Suddenly the 'cheap' flight turns out not to be quite such a steal after all.

Baggage fees

Take note of the luggage limits and aim to travel as light as possible. Packing too much can result in excess baggage charges. It's not just your suitcases that you need to worry about -- even your hand luggage can get you into trouble if it's over the limit. Exactly how much you can expect to pay depends on the airline.

Hotel charges

The mini-bar of goodies is an obvious one, but what you may not be privy to are the hidden surcharges that some hotels add for things like a second daily housekeeping visit or shuttle service, a "resort fee" for usage of the gym and business center, extra charge for early check in or out, even for a towel at the pool or for the newspaper that shows up at your door. Look at your bill before you check out, and question any unexpected charges.

Credit and debit cards charges

Do you plan to use credit or debit cards while you're away? Watch out for hidden charges on top of your transaction. Don't assume that debit cards are exempt from this -- this can happen at ATM cash machines, too. Foreign banks can be the worst places to make cash withdrawals. On top of the typical handling fee for making the transaction, there may also be a commission added to further bump up the costs. You'll be charged each time you make a transaction so it can be more cost-effective to withdraw enough to last a few days rather than making separate withdrawals throughout your trip. (Remember to stay safe if you're going to be carrying cash on you though!) Some cards have high fees attached if you'll be spending abroad. If this is true of yours, a pre-paid card may save you money. As long as you have loaded the card with the relevant currency, there are no hidden fees to worry about.

Car hire

Check how much you'll have to pay if you have an accident. Even with insurance, there may be a fairly sizeable excess involved. Some rental companies add fuel surcharge to the overall bill and this can up your costs considerably. Check whether your own car insurance will cover you for driving a rental car before you agree to pay for their insurance.

Airport parking

Leaving your car at the airport can be expensive -- you'd likely be better off taking the taxi instead.

Internet usage

Want to use your smartphone to access the Internet while you're out of town? This could be costly. Make sure that you know how much data you're using and how much this will cost you. Where possible, look for free Wi-Fi hotspots. (Try apps that locate free connections like the Free Wi-Fi Finder.) Check the price of making and receiving calls and texts abroad, or try emailing your family instead.