If you plan to stay in Latvia for a longer period of time, it is useful to pick up some Latvian as it may be difficult to get along without it outside the tourist areas. Especially as older people seldom understand English and speak only Latvian and Russian.
The National Integration Centre offers Latvian courses free of charge, but there is a waiting list. There are several providers of paid language courses:
Several of the schools above also offer individual language lessons. Alternatively, you can learn the basics on your own, for example, with the help of books or free online materials such as the ones prepared by the Teach and Learn Latvian project.
An exchange partner is an excellent resource for practicing a new language with a native speaker. As an added bonus, language exchange partners can help you understand the culture of the area and inform you of local happenings. Questions about gift giving, festivals, nightlife, and greetings can be addressed without worry. In the best case sceneries, an exchange partner is not only your ambassador, but a friend. Find a tandem partner through EasyExpat's forums.