There are competent residency attorneys in Costa Rica who can assist you throughout the process.  Selecting a residency attorney is a personal choice but make sure to get references or, if possible, a personal referral from someone you know who has gone through the process. Government fees are fixed costs and attorney fees can vary.  It is a good idea to review all related costs with your attorney up front.

Here is a summary of documents that you will need to submit:

•       An apostilled(1) birth certificate.
•       An apostilled(1) criminal record check issued by your home country where you legally resided for the three prior years.
•       If married, a marriage certificate.
•       Copies of your current, valid passport.
•       Recent passport sized photos.
•       Fingerprint registration in San Jose.
•       Residency application and application letter directed to the Director Legal of Migration.
•       Proof of consular registration of your intent to apply for Costa Rica residency.

The Hague Convention Abolishing the Requirement for Legalization for Foreign Public Documents, the Apostille Convention, or the Apostille Treaty is an international treaty drafted by the Hague Conference on Private International Law. It specifies the modalities through which a document issued in one of the signatory countries can be certified for legal purposes in all the other signatory states. Such a certification is called an apostille (French: certification). It is an international certification comparable to a notarization in domestic law, and normally supplements a local notarization of the document.  Source:  Wikipedia

If your home country is not party to the Apostille Convention, documents must be submitted to the Costa Rican consulate in the country of origin and then authenticated at the Foreign Affairs department in San Jose.