Ubud is located in the middle of Bali, and if you're planning on getting there via flight, you really need to go to the Denpasar Bali Airport, which is located on the southern tip of the island. From there you can either rent a car or take a bus to get to Ubud. The island isn't necessarily huge, but it can take a while to get there because of the terrain, and not all of the roads are paved very well. Also, every year the roads get damaged due to the rains and harsh weather, so this can also slow things up a bit. If you are going to rent a car, you can either get a car from a few different agencies at the airport, or you can rent one right outside the airport. The only difference is that you might have to pay a bit more. If you take a bus it probably won't be a very comfortable ride, but you'll be saving money on renting the car and the gas for the car. Also, you won't have to worry about it once you get to Ubud. If you want, you can rent scooters or mo-peds when you get to Ubud, and this will help you get around, but it is not needed. Many backpackers come to Ubud every year, and they don't seem to have a problem with the transportation, so it should be all right. If you are staying at an expensive and luxurious hotel or resort, they can probably arrange for a pick-up for you at the airport.