Travel advice: How to avoid sneaky budget airline charges

They've been at it yet again. According to the price comparison website travelsupermarket.com, many airlines have been ratcheting up charges for extra services over the past 12 months.

In its annual study, the website has revealed that fees for checked-in luggage, overweight bags, allocated seating, priority boarding and ticket changes have all risen.

Soaring costs: If you fail to check in online with Ryanair, you have to pay more at the airport

The biggest of these hikes include a 47 per cent rise (from £15 to £22) with Thomson for taking a checked-in bag to Majorca, and a 50 per cent increase (£20 to £30) with Ryanair for travelling with a child aged under two years on your lap.

While some extra charges imposed by airlines are impossible or difficult to avoid, others can be bypassed - or at least kept to a minimum.

Here are eight golden rules for keeping the costs down.

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Travel with just hand baggage

Ryanair has the highest fees for checked-in luggage - it will cost you at least £70 per bag on a return flight to the Canary Islands this summer. But virtually all the other so-called budget airlines have steep charges for putting a bag into the hold, and even British Airways has just introduced lower hand luggage-only fares on its short-haul flights from Gatwick.

If you are checking in bags, pay in advance

Leave it until you're at the airport to check in that bag to the Canaries this summer with Ryanair and you'll fork out £130 one-way (you're unlikely to make the same mistake flying back). With most other budget airlines, bag fees paid at the airport are also significantly higher compared with paying in advance. Note, too, that Ryanair now charges £5 more per bag per flight if you add it later to an existing booking rather than paying for it when you make your initial reservation.

Stick to your allowance

Exceed checked-in baggage weight restrictions and you risk paying punitive fees - for example, it's £20 per kilo with Ryanair.

Be clear, too, on rules covering the pooling of allowances for checked-in bags: some airlines, including easyJet, allow it for those travelling on the same booking, but others, such as Ryanair, do not. Airlines are all too keen to penalise passengers when carry-on bags are larger or heavier than the permitted figure. Monarch charges a whopping £50 to put overweight or oversized hand luggage in the hold.

Hold on: Like most budget airlines, easyJet charges extra to check a bag into the hold

Skip paying for selecting a seat or priority boarding

Most airlines offer allocated seats for free, and promise to try to sit family members together. So, at least on short-haul flights, I don't think paying extra to choose specific seats is worth it. For example, a family of four pre-booking standard seats on return flights with Flybe will pay at least £52 more.

Check in early to increase the chances of sitting together. Ryanair is one of the few airlines to persist with mostly unallocated boarding. Instead of forking out for its priority boarding (£56 for four passengers on return flights), just get to the departure gate early.

Check in online with Jet2.com and Ryanair

Opting to check in at the airport with Jet2.com rather than online usually means paying a fee. If you do choose the online option with Jet2.com, be sure to print your boarding card beforehand and take it with you, otherwise it will charge you £17.50 to issue one at the airport. With Ryanair, fail to check in online and print off your boarding pass and you're liable to pay its £70 Airport Boarding Card Re-Issue Fee.

Get everything right the first time on your booking

Airlines impose swingeing fees to make changes. With Ryanair, a name change costs between £110 and £160, and a flight change costs from £30 to £90 per passenger plus any increase in the new fare.

Pay by debit card

Last month, the Government introduced a ban on excessive fees for payments made with debit and credit cards - good news for travellers, as some airlines were among the worst offenders on this matter. Debit card fees for purchasing flights have all but disappeared, but credit card charges still apply: with Flybe, it's three per cent or a minimum of £5. Bear in mind, though, that paying with a credit card does give you extra consumer protection. EasyJet and Ryanair levy unavoidable 'administration fees', but at least they are included in their initially quoted fares.

Choose your airline carefully

Don't simply go for the airline with the lowest headline fare. Supplementary charges vary enormously, so calculate the total of cost of flying, with extras, before booking.

The Civil Aviation Authority website has a useful, regularly updated chart of airline fees - see www.caa.co.uk/docs/2200/ Comparing_airline_charges.pdf.