You'll be hitching from Rigas Iela (Rigas Street) towards Riga
There are two options here:
1.) * Take the local bus from the bus station in town to the last bus stop along Rigas Iela.2.) Walk * Or walk to the last bus stop along Rigas Iela in the direction of Riga.
Either way, this is the place to hitch. I got a lift within 5 minutes while holding a sign.