By Bus Or Bemo
There are daily shuttle bus services from Ubud which are widely advertised locally there. Book 24 hours in advance.
Kintamani is served by bemos and buses from Batubulan terminal in Denpasar for about Rp 25,000. These are torturously slow though.
Organised tours to this area are widely offered in all major centres of Bali.
By car
Kintamani is usually approached from the south with 2 routes in from Ubud 45 minutes, and one each from Besakih 1 hour and Bangli 30 minutes. There is also an easy way in from the north via a turning off the coast road east of Singaraja 1 hour. All private vehicles pay entry charge to get into the area of Rp 10,000 per person. Keep the ticket as this is valid for the whole Kintamani area, and you may be asked to show it again.
From the popular tourist destinations in South Bali, a trip to Kintamani by car will take 90 minutes plus.