Record yourself speaking naturally and then play it back. On playback, listen closely to how you speak and say each word. Identify the words or phrases where your Tagalog accent is most noticeable and that you want to work on fixing.
Study the English language intently. Use textbooks, reference books or websites to study different nuances of the language, such as grammar, word order phonetics and the various sounds used in the language. Utilize the help of a tutor or English instructor for additional guidance.
Practice proper pronunciation of English words. Concentrate on sounds like the "v" sound, "f" sound and "th" sound, all of which don't exist in Tagalog. Practice saying those sounds clearly and correctly (i.e. "the" instead of "da") until you have them right.
Speak English conversationally as often as possible. Listen to how others speak to you and attempt to mimic their American accent. Speaking English often will help you to feel more comfortable and fluid in the language and help you break away from the accent Tagalog requires.