Bangkok is safe place to travel on. If you are walking alone you will not have any kind of problem even at night. Transportation between destinations in Thailand is easy and most of people speak at least some English. But the problems are some scams and stealth crime that you will likely encounter - watch out in particular for smooth talking con artists and talented pickpockets that operate in crowded conditions such as markets and the Bangkok buses. Keeping your wallet or purse in a money belt can be helpful at preventing the thieves.
