We can only say this to little. If you drive car, motorbike or anything else in Thailand you have to pay attention. In Thailand almost 80 people loose there lives every day and why is this? The thai do not follow the speedlimits and its allowed to drive left and right side. If you go to the expressway you will still be able to meet motorbikes, tuk tuks and sometimes bikes. If you want to drive in Thailand the most safe way is to rent a car and we on everything in Thailand.com always rents one from the airport. Just make sure to buy the extra insurance that cover everything, it is more expensive, but if anything happends it is the cheapest insurance you will ever buy.
The traffic is not getting better after dark. Here you have to watch out for everything and many thai people drive with no lights.
We normally rent a car and nothing happend yet. So just be careful and always think that the roules in Europe or US is not the same here. Always be ready for a dog to run in front of your motorbike or car. Always be ready for the car behind to take over with at least dubble speed of your own.
And hey, when you get the hang of driving in Thailand it is not that difficult and you can rent really nice cars for low money.