Taxi drivers, local tour companies and official-looking badges can't always be trusted by travelers.

Taxis are a common ruse for a scam. Never get into a cab unless you're sure it’s reputable, and always agree on a price beforehand.

Beware taxi drivers (or "helpful" strangers) who tell you that the hotel or attraction you want to go to is closed or fully booked. They are often paid commission by other hotels and restaurants to take you there instead.

Always double-check, through word of mouth, guidebooks or the internet, that local tour companies are reliable. Some will add unwanted extras to your trip (in exchange for commission), while others may take your money and vanish. Many ‘cheap’ buses taking non-locals across the Thai-Cambodian border, for example, fall into the first category.

Pressured buys are a favourite tactic. In Beijing, for instance, you may be invited to a traditional teahouse or art exhibition, and then presented with a huge bill or guilt-tripped into an expensive buy. Beware attractive strangers who invite you to bars only to vanish when a huge bill arrives.

An official-looking badge or uniform gives an extra layer of authority. If you are asked for cash or for your passport in an unusual situation, insist on checking with a police officer or senior-looking official first.

Lastly, refuse all unsolicited offers to buy goods that you are told you can sell at a profit back home. This is known as the gem scam. Despite all this, don't make paranoia your default setting when stepping off the plane. For one thing, scams are common enough at home – check out Directgov for some well-known examples.

This article was published in partnership with Lonely Planet Magazine.