Choose reading material on subjects that you enjoy. This will help to motivate you and keep things interesting.
Read a variety of different texts. You can see how English is used in different ways. Discover its artistic usage in fiction, its more formal usage in newspapers or its colloquial, slangy usage in blogs.
Do not make things more difficult on yourself by reading too far above your English level. Remember that a new language is a difficult thing to master. There will be plenty of time to tackle more complex reading material. If you are a beginner, an English reader with a side-by-side translation (English on one page, your native language on the next) may be ideal.
Do not look up every other word in the dictionary as you read. This will only slow you down. Instead, read to get an idea of what the piece is about, quickly noting down or highlighting new words and phrases. Rely on what you already know and try to figure out what the words mean from context clues (hints from the context itself as to what the meaning is) and cognates (words that are similar to those in your language) to figure out what you don't.
Observe how words and phrases are used in different situations, as well as grammatical structure and syntax.
Look up the words you couldn't figure out in the dictionary once you have finished reading. Keep a list of new words and add them to your mental store of English vocabulary.