A wonderful way to enter Burma/Myanmar is to go by boat across the Estuary from the Thai City of Ranong. Itself a nice destination.
Go to the docks in Ranong and negotiate a passage to Burma with some of the local boat drivers. You'll have to go on a Motobike taxi, just say I am going to Burma Ferry, and the Moto driver will know to take you automatically to immigration (which is curiously in town) first. Actually This is strange. After going to the Ranong Immigation Office, where you have officially left Thailand, then you leave and you are still in Thailand. Its strange. THere is nothing to stop you from travelling as an illegal tourist. But I wouldn't. :oS
The passage to Kawthoung in Burma should cost no more than 300 Baht one way. But You will need to bargain. Starting Price will be around 700 Baht.
Arriving from Thailand, it's a short hop from Ranong to Kathoung. There is no regular service, but there are plenty of fishermen boats that will give you a lift for a few bath or even for free. Once you arrive in Myanmar proceed to the police office. Officially you need a visa and you're not allowed to enter Myanmar from here. Actually it works like this: you leave your passport in the police office, you pay about 15US$, they give you a piece of paper written in Burmese and when you leave Kawthoung back to Thailand they'll give you back your passport. It seems you are allowed just to stay in Kawthoung for a limited amount of time (usually just one day; be clear about this with police). It's a bit scaring to leave your passport there, but I didn't have any problem and it looked like it was common practice.
Transport to Kawthoung (Victoria Point) is probably easiest from Ranong, Thailand which is located about 30 to 40 minutes by long tail boat just across a wide estuary that empties out into the Adaman Sea. It is possible t fly into Kawthoung from the capital of Yangon, Myanmar...but it was our experience to hire a boat and driver from the docks in Ranong for 400 baht. You must negotiate the fee with the driver or whichever tout brought you to the boat. It seems the going price for the passage is between 300 to 400 Thai baht. The boat makes several stops during the crossing to present your documents to various immigration officials on both the Thai and Burmese side of the border. It can be a bumby ride as was our experience in the choppy waters. Once you land at the jetty in Kawthoung the boatman should wait for you...if not...you will have to hire another boat for the return trip to Thailand. Be sure to have your papers or passports in order before daparting the docks on the Thai side.
Kawthoung is accessable from Ranong in Thailand. Many people only use the boat to exit and reenter Thailand, thereby allowing them to stay another 15 days. If you want to stay you have to pay $10 in crisp bills. If you come back in a small group you'll have to negotiate with a boatman to take you back.