To Bali: there are many routes to Bali, but generally all involve flying to Denpasar.            If you’re coming from Thailand, Malaysia or Singapore, it’s inexpensive to buy tickets online with various no-frills airlines(Air Asia has flights from Kuala Lumpur to Bali, and connecting flights to Bangkok/Singapore, Tiger Airways goes from Singapore,etc ).

Getting to Ubud from the airport: once you’re through the gates, you will walk outside and find a pre-paid taxi booth with fixed rates. Taxis/minivans to Ubud are 175, 000 rupiah (about $20) and the drive is about 1 to 1 1/2 hours. If you arrive in the daytime, there are also cheap shuttles that will drop you in Ubud (slow)

Once you’re in Ubud, it’s easy to get around on foot. Scooters are common and inexpensive to rent ($3-5 / day)