Create your reading environment. You will need to concentrate, so find somewhere quiet, with no distractions. Make yourself comfortable, calm and ready to focus. Make your reading environment well-lit, and if you wear glasses, use them. Sit with a good posture - keep your back straight with your feet flat on the floor and your material close enough so that you don't have to stretch, or strain your eyes. Breathe well, with slow, full breaths.
Scan your chosen text. When you are scanning, you are looking for a piece of specific information or text. Using this technique, you ignore everything apart from what you are looking for. If you are not looking for a specific piece of information, but want to ingest the wider text quickly, you will need to use a different technique, such as skimming over the entire text.
Skim the text if you're not looking for a particular thing. Look over the whole text with slightly less focus than you usually would, trying to focus on whole sentences rather than individual words. Skim over parts of the text that are irrelevant or uninteresting - prioritize and find the point or details over the filler. If you tend to vocalise or semi-vocalise your words as you read them (if you use a voice that reads along in your head as you're reading), try to avoid doing this - it slows down your reading speed.
Use a pen or a pencil to guide your eyes. This should help you to sub-vocalise less, and help you skim more efficiently. It will also help you keep your place, stopping you from re-reading material.
Practice and test your reading speed regularly to gauge your improvement. An average speed is 200 words per minute, while top speed readers can read up to 1,000 words per minute. A good way to measure your performance is to use the test in Resources. Attempt the test by reading at your normal speed, before you implemented these new techniques, then implement the techniques and note your improvement. Attempt to double your reading speed. The better your reading speed is initially, the harder this may be - but it becomes more natural and easier with practice.
You may notice an instant improvement, but keep practising what you have learnt, otherwise your reading speed will return to normal.