Shop around and don't just buy the insurance from your holiday provider as it's usually more expensive and the cover is not as large. Also don't forget to take your European health insurance card as this entitles holders to free or discounted treatment from state-run hospitals and GPs in any European Union country plus Iceland, Leichtenstien, Norway and Switzerland. Apply at ehic.org.uk and allow a good week for processing.
Never, never buy it at the airport. You can order money in advance from specialist providers, like AceFX. Also be careful of using credit cards on holidays as some charge a foreign exchange loading fee as well as charging up to £5 per cash withdrawal.
Always pre book your car and shop around for quotes. As the Sunday Times said: "When booking any hire car, watch out for additional charges which can substantially bump up costs. Research by iCarhireinsurance.com found that a family hiring a standard family car in Malaga over the Easter week, could end up handing over an additional £352 in extra fees at the rental desk when picking their car up. For example, hiring a car with Hertz for the week would cost £280, but adding an extra driver would bump up the price by £74, while including a child's seat would cost £67. Booking a Sat Nav would cost a further £81, while excess car hire insurance would cost £130. Drivers should therefore take their own added extras wherever possible. You can reduce the cost of excess car hire insurance by taking out standalone cover before you go. This costs £2.99 with iCarhireinsurance.com, or you can buy annual cover for £39.99.