Listen to news programs on the radio. Repeat words that you have difficulty pronouncing. Pay attention to the sentence structure used by newscasters.
Watch television news programs. Again, repeat the pronunciation of words and pay attention to the sentence structure used by newscasters.
Play accent reduction CDs in your car and at home whenever possible. These CDs can be purchased online or borrowed from many libraries. If you do not have a CD player check to see if your library has players available for in-library use or for check out.
Practise speech and grammar with online games. A site called FunBrain (funbrain.com/words.html) has vocabulary, grammar and word comparison games. The English Media Lab (englishmedialab.com) has many games with online pronunciation exercises. ManyThings (manythings.org) has vocabulary, speaking, listening and singing games. For those who do not have access to a computer or internet, check to see if your local library has internet sign up times available.
Read and study language structure in English reference books. "The Elements of Style" by William Strunk and E.B. White is one of the most well known reference books on English language rules and usage. It is readily available at libraries and bookstores.
Sign up for English as a Second Language classes at your local community center. Many community centers across the United States offer ESL classes to residents at no cost. These classes are appropriate for native English speakers as well as non-native speakers.