.Car: coming off the E75 National Road, take the Spili/ Timbaki interchange, and drive up the hill away from Rethymno. In 6 minutes you will pass the turn for the PostMinoan cemetery. At the next turn off, either turn right for Kastellos and Ano Valsamonero, or stay on the road for Armenoi. Link to Google Maps here
Bus: This is a link to the KTEL bus website, which will give you up-to-date information on bus journeys to Kastellos, Armenoi and Ano Valsamonero, and further afield... There are regular bus services all along the National Road into Rethymno bus station.
Taxi: The Markidis family taxi firm are a local firm who do airport runs, short trips to and from Rethymno and the local area, and can also make day or half day sightseeing trips. If you're keen on seeing something that isn't easily accessible by public transport, this can be a good option. Call (0030) 6973358624 for their 24 hour line in the taxi.