Guarani is a small South American native nation located a bit north of the La Plata region. In 1444, Guarani is very isolated, like some of the other native nations in South America. Guarani exists in campaigns started between 1444 and 1756, making it the last of the original nations in South America to be conquered by the Europeans.
The below is one of many player suggested strategies for Guarani. Bear in mind, due to the dynamic nature of the game, it may unfold differently for other players.
All native OPM tribes can select one of three strategies. The first is to migrate toward either the Incan or Aztec territories, merging with those societies and hopefully conquering them. This can bring the advantage of better technologies and access to gold, but also includes a greater risk of early defeat. The second option is to develop, either within the interior or along the coast. Developing along the coast will expose the tribe to attacks from the Europeans, although there are some good coastal provinces, namely (for the Guarani) Rio de Janeiro. Moving inland one province is arguably safer, as the tribe can quickly reform when a European power lands along the coast. If one wishes to delay reforms, moving into the heart of South America may be viable, as the player will gain more time to colonize a large realm. The third option is continually migrate, and never develop, which doesn't appear to be particularly viable over the long-term.