A few things I would advise,
1. spend the extra money and fly Thai Airways BKK-HKT and you can fly on a 744 for the hour flight, get there early and ask for the exit row. Thai flies 744s x2 777s x2, 332 and 300 all to HKT.
2. Google Top Thailand scams.
3. Stay away from the Tuk Tuks in BKK because they will scam you and drag you to all these places saying they will get a free fuel card if you go, and those things are death traps.
4. When arriving in HKT go straight to the taxi stand to the right when you come out of the airport, DO NOT go with a taxi driver that approaches you before you get there, they will drive you all over the place, trying to get you to go in places they get kick-backs for, and you will end up in some seedy parts of town.
Stay Safe! Phi Phi Island is a must.