As far as i know only Riga has international flights. So you have to find tickets to Riga even if you plan to go to other cities of Latvia. You can use transport options from Riga to other cities.
From airport to city center
Passport control is not a big problem. As it is a small airport most of the time it is not so much crowded. You may pick your luggage quickly and go out. You may buy a one way bus ticket from Narvesen (Markets chain in Latvia) or from tourist desk which is 1.15 €. But you may also pay in minibus. It is 2 €. Number 22 goes directly to city center. It takes around 15-20 minutes to arrive.
Most of the transports cross infront of Origo mall. So if you booked your place at city center then you may hop off at Origo mall. It is not a long distance to walk around from there.
There are some taxi companies in Latvia. Baltic Taxi, Riga Taxi, Red Cab, Panda Taxi… They all have different pricing policy. Baltic Taxi has the most vehicles. And it is the most expensive one as it was told to me. Panda Taxi has the minimum vehicle so they are the cheapest one. So you may consider this when you choose a taxi. But you may also download Taxify application and call taxi from there. So you may see what you will pay. It should be less than 10€.
Last option is to rent a car which i don’t have any experience about. So i can not suggest you anything about this.
Transport in Riga
Inside Riga your only options are autobus,tram or taxi. They don’t have metro line. And i don’t think they need it.
For taxi you may ask your hotels reception to call any company you prefer. For others you may buy one use, daily, weekly tickets from Narvesen.
Transport between cities
Main train station of Riga is inside Origo mall. You may get inside Origo mall and check train schedules, prices and buy tickets. You may go to other cities of Latvia or to other countries.
Main bus station is also close to Origo mall. There is Stockman mall next to Origo mall. And behind Stockman you will see the main bus station of Riga. There is no train to every city of Latvia so this bus station is more usefull for transport between cities. You may also go to other countries from here. For example if you have a Baltic tour instead of a Latvia tour then you may go to Vilnius/Lithuani or Tallinn/Estonia from here. Both are around 6 hours.
Have a safe travel 🙂