Latvia is small enough that most destinations are reachable as day trips from Riga. Trains run from Riga to Jurmala, Sigulda, Cesis, and Daugavpils; the rail network is run by Pasažieru vilciens. Fares are low — almost anywhere in the country costs under €20 by train.
For places the train doesn't reach, intercity buses fill the gap. Liepaja, Ventspils, and Valmiera are well served by bus from Riga's main bus station (Autoosta), which is beside the train station. Lux Express and regional operators run reliable services.
Renting a car is the most flexible option if you want to explore the coast, the Gauja Valley, or the remote eastern Latgale region at your own pace. Rental offices are plentiful at Riga Airport. Latvia drives on the right; speed limits are 50 km/h in towns and 90 km/h on open roads. Note that headlights must be on at all times, and the drink-driving limit (0.05%) is strictly enforced.
Within Riga, trams, buses, and trolleybuses cover the city well from around 05:30 to 23:30. Bolt and Uber both operate; fares are low by Western European standards.