From Thailand: Cross over the friendship bridge four which spans over the mighty Mekong connecting Houay Xai with Chiang Khong on the Thailand side. To cross the bridge, you need to take a bus which costs 20 Thai Baht per person. On Arrival visa for Laos can be easily obtained at the border by paying appropriate fees.
There are daily bus services from Chiang Rai, Thailand, which costs 220 Thai Baht per person and takes about 2.5 hours for the journey.
From Vientiane and Luang Prabang: You can fly in from Vientiane and Luang Prabang to Houay Xai which runs three times a week. There are also buses available from Vientiane and Luang Prabang which takes about 6 to 8 hours and takes about 20 to 30 USD per person.
From Luang Namtha: One of the nearest towns to Huay Xai is Luang Namtha. A bus from Luang Namtha drops you at the Keo Champa bus station in Houay Xai. The journey takes around 4 hours. As the bus station is about 5 km outside the town, it costs 10,000 LAK by tuk-tuk to reach any part of the city.
Since most of the sites to see are concentrated right in the centre of the town, the best way to get around is on foot. If you want to explore further, you can easily rent a bike from your hostel or a nearby rental shop. You can pay for the motorcycle by the hour or by the day.
To get even further you can tuk-tuk which is present everywhere. It will cost you around 10,000 LAK to get to the morning market.