1. Read fun things: The most important thing is to choose texts that you care about. If you can't stop reading, that means you've chosen a good text. It does not have to be intellectual, it does not have to improve your knowledge of science or history. Don't feel guilty about reading comics, magazines, detective stories, romances, blogs, etc.
2. Read "n+1" texts: What does it mean? If your current English level is n, you should choose texts that are one level above, but not more. You want to learn something, but you don't want to come across a new word or grammar structure 3 times in each sentence. There's a simple rule here: if you're not enjoying the text, switch to an easier one.
3. Read texts written in "everyday" English. If you want to use contemporary, natural English, you have to learn contemporary, natural phrases. Not all texts contain such phrases. Many books contain literary phrases that are simply not used by normal educated native speakers.
4. Start by reading texts by the same author (or texts on the same subject). Each author has his/her own vocabulary and grammar. For example, when you read a book by Michael Crichton, you come across a lot of scientific vocabulary. Afterwards, it is easier to read another Michael Crichton novel than to read a book by a different author.
If you are a beginner reader, jumping from author to author (or topic to topic) can cause frustration because every new text will seem difficult. You may feel like you are making no progress. This is not healthy for your motivation. Reading a few similar texts gives you a sense of accomplishment, which can be very motivating.
