A lot of people thinking of a trip to Thailand ask me about Snakes. Is it dangerous to walk around? There is a lot of info on the internet, with a lot of pictures of just about every snake that lives in the Kingdom, and I recommend you have one of these sites with lots of pictures bookmarked in case you need to identify one. The best site I have found is Snake Info pages of the Siam-Info website.
Even though there are about 200 varieties of snakes in Thailand, and about 60 of these are venomous to people, you are not likely to be bitten by a snake on a vacation. Maybe about the same odds as being struck by lightening, but your odds might get a little worse if you do a lot of hiking in National Parks in Thailand. If you stay in Thailand for a long time, maybe as an expat resident, chances are you will see a snake or two sometime. Don’t panic (easy for me to say sitting at my computer).
REMEMBER, Snakes are not looking for you. You are not a target, and they would just as soon depart quickly if they see you. They are not going to chase you.