what would you look out for at home when doing the same??
essentially Thailand is a "SOFT" destination, petty crime etc is less than in your home country (Europe/USA/Oz).....but everywhere in the world has psychos and thieves....why should Thailand be different?
How can anyone write down every conceivable situation....use common sense - if you have to be told ten re-think - travellers who have problems are so often the ones who are either too naive or too careless to be travelling alone. If you doubt your ability to look after yourself, trave l with someone else.
Just use your common sense. Would you go walk alone on a quiet beach alone at 2 in the morning (lots of muggings of this kind in Pattaya) or get drunk and slap a policeman in the face who is holding a guy (a Canadian was shot last year in Pai for exactly this).
Without meaning to repeat points already made by previous posters:
Thailand is a very safe country and there are so many backpackers there. You only need look at the number of Thailand posts in this Asia forum!! People go there as it is easy to travel around, cheap, safe and not as daunting a destination as other parts of the world. Added to that is the ease of visiting other se asian countries nearby. The infrastructure is well-established in thailand and the healthcare facilities are pretty good! I could go on but will spare you...
I would suggest that I felt less at risk there (admittedly as a 23yr old bloke not a young female) than I do on a night out in certain parts of the UK. Thai people are friendly, polite and generally very gentle in nature. There are undoubtedly some scammers and bastards about - they are everywhere. So:
-apply basic common sense
-don't walk around at night on your own, especially if you have had a drink or two (you wouldn't do this at home I imagine) as this just increases the chance of unpleasantness
-don't think that everyone is out to get you - most people are really cool
-definitely try to avoid people taking drugs or taking drugs yourself. Weed is available and all manner of speed/pills etc etc. Beware the risks are serious and no-one wants to find out about thai prison conditions!!
-watch out for 'over-friendly' people offering you drinks, food etc on overnight trains or whatever. Just politely decline.
-don't buy any gems. Oldest trick in the book.
-don't carry lots of cash around
-look after your passport and take photocopies stashed all over your backpack etc.
-walk around with a sense of purpose even if you are unsure where you are going
-don't walk around with your guidebook in hand too much. Makes you look unsure and green.
-IF YOU GO TO A FULL MOON PARTY MAKE SURE YOU STAY IN A SECURE AND SAFE GUESTHOUSE WITH A GOOD REPUTATION. HUNDREDS/THOUSANDS OF BACKPACKERS ALL OUT GETTING DRUNK INEVTIABLY LEADS TO TROUBLE AND THEFTS FROM ROOMS ARE QUITE COMMON. THAT IS A FACT AND IF OTHER POSTERS SAY I'M BEING SENSATIONALIST THEN SO BE IT. I HAVE SPENT 4 MONTHS TRAVELLING IN THAILAND ON VARIOUS TRIPS AND KNOW I AM NOT TALKING SHITE
Above all, Enjoy it!! You will have a brilliant time and will probably fall in love with the easy going nature of the people and the country. Koh Tao is a superb little island - IF YOU GO THERE YOU WILL HAVE A GREAT TIME!
Hope this helps,