Fantasising about white sands, tropical palm trees, warm crystal waters ...? Well, WAKE UP! Even if you've already booked an overseas holiday this summer, there’s work to be done to protect your pocket, so you’ve more cash to spend on enjoying yourself (or to make it easier to stick within your budget).

It may seem early, but actually that’s the point – the later you leave sorting out holiday essentials, the more difficult and expensive thinks get. So long before you chuck your bikini or trunks in your case, follow my holiday MoneySaving need to knows and save yourself £100s.

Permanently holster unbeatable exchange rates

Forget cash, travellers cheques or bureaux de change. You can smash these exchange rates with ease for every holiday you go on. The unexpected saviour here is a credit card – not just any card though, one of five specialist cards. These give special cheap spending when abroad, in the hopes you’ll also holster the card at home. But don’t bother – I pop mine in my overseas travel wallet and it only sees the light of day in the sun.

To understand why they’re good, you first need know that all plastic providers get the Visa and Mastercard wholesale exchange rate, which is near perfect. Yet most add a hidden 3% load to the rate they give us. So spending £100 worth of euros costs £103.

Specialist cards are load-free worldwide, meaning you get perfect rates. These cards are Halifax Clarity, Saga (over-50s), Post Office, and, for Nationwide customers ONLY, its Select card. If you have a Santander Zero credit card, that’s also load-free, but no longer available to new customers.

Only do this though if you pay off the card in full each month, preferably by direct debit, to minimise the interest. For a full card-by-card breakdown, showing which is best and easiest to get for you, see www.mse.me/travelcards.

Beware debit cards abroad

Bizarrely, the very worst way to spend abroad is on what I call the debit cards from hell. If you have a Santander, RBS, NatWest, Halifax or Lloyds card, then not only do they add a hidden load to the exchange rate, they also charge a fee of between £1 and £1.50 penalty each time you spend on the card. So buy something costing £5 worth of euros and you’ll pay up to £6.50 for it.

Get travel insurance NOW or you mightn't be covered

If you've booked and don't have insurance, you're not covered for cancellation or collapse. Go away more than twice a year including city breaks, and policies covering a year’s travel are usually cheaper.

The current cheapest European annual cover is £16 for a single person, £30 for a family. Full explanation and top value picks at www.mse.me/travelinsurance. If you are going away just one time, then www.moneysupermarket.com, www.confused.com and www.gocompare.com have comparison tools to find cheap cover.

If you’re not online, it's costlier but most of the major supermarkets offer reasonably cheap policies. It's worth checking out which is cheapest for you.

Ensure you know how to turn off smartphone data roaming

Even if you don't use the web overseas, apps can download £100s of data in the background. So you need to know how to turn off data roaming to protect yourself. Most phones have the option in settings – it's worth finding it now.

One of my site users, motbofres, really suffered: "Went to India and US, got back and Orange was taking £3,000 for data. I wasn't heavily using the web, just checking my email and maps. I left data roaming on for 50% of the time."

Plus never watch TV via 3G – mobile web watchers pay hideous penalties when they return, for example, Three charges £10/MB in Canada. As a 30min TV programme hoovers up 500MB, an episode of Hollyoaks could leave you paying £5,000.

Book cheap car hire sooner and beat hidden nasties

If you need car hire overseas this summer, sort it ASAP. Car hire booked in advance can be as little as £10/day. Use comparisons www.kayak.co.uk/cars and www.carrentals.co.uk to find your cheapest.

One thing to watch out for is many cheap firms charge upfront for a full fuel tank and let you return it empty. For low mileage drivers, this can add £100 to the cost. Factor it in and pick a smaller car for a smaller fuel tank.

Often car hire comes with collision damage waiver insurance that covers the car if you have an accident. Yet these often have huge excesses of £500 – the amount you pay before insurance kicks in.

To cover this problem of their own making, car hire companies push costly 'no excess' insurance. Check if you can get excess cover for a fraction of the cost via comparison site www.MoneyMaxim.co.uk.

Find the cheapest foreign currency

Never change your currency at the airport. They know you’re a captive customer, and you get hideous rates. If you’re so late it’s the only option, at least call up in advance and pre-order when you tend to get an improved deal.

To find the very cheapest deal, ignore “commission free” sales spiel. Instead just ask “if I give you £300 how many dollars will you give me after all fees?” and compare that way. If you’re online, my www.travelmoneymax.com tool compares all the best rates.

Slash the cost of airport parking (don't pay on the day)

Public transport’s cheap and accessible for most airports, yet many still drive. If so, the sooner you book parking spaces the cheaper. Comparison sites like www.aph.com and www.Skyparksecure.com hunt for you. Also consider booking a night in an airport hotel. They sometimes offer a week's parking with a night's stay, which is occasionally cheaper than parking alone elsewhere.

Don't Google to get/renew EHICs, passports and ESTAs

Many shyster sites appear, looking like official sites, but charge extra fees for nowt. Three to watch out for:

a) EHICs are always free. The European Health Insurance Card gets you treatment at EU state-run hospitals and GPs at the same cost as a local. So if it's free for them, it's free for you. Millions have expired though, so check yours is still in date – and always take it with you. The official site is www.nhs.uk/EHIC .

b) ESTAs only cost $14. If you're going to the US, go via the official ESTA site at https://esta.cbp.dhs.gov.

c) Passports via Gov.uk. Passports can be costly at up to £137. To ensure you're not paying more than needed, go to gov.uk/renew-adult-passport.