As you would expect, US dollars are the easiest currency to change into pesos and you’ll find the best exchange rates at banks and independent Bureaux de Changes (Casas or Agentes de Cambio). Bear in mind that larger sums of foreign cash brought into the country must be declared on arrival, though there is no limit to how much can be imported in travellers cheques.
For larger amounts of money, most expats will want to consider bank transfers from overseas. As usual, there can be high fees involved, especially if you’re considering wire transfers (these are nearly always a bad idea, except in emergencies). Consider speaking to a specialist foreign exchange broker such as Skrill or HiFX, particularly if transferring large sums for property investment. Fees can vary, so make sure you shop around before committing.
Transfers within the Dominican Republic are fairly straightforward and can be done quickly using internet banking, or in branch.