The best way to learn or improve reading is to choose the easiest letters first. Like any alphabet you must first learn by rote, memorizing each letter one at a time. While these letters may take a long time to learn initially they will make it much easier to read.
I have found that it is easier to learn the letters in groups when beginning. You choose a group of four letters. Reading can start with just these four letters and with every group you add there will be a significant improvement in reading ability. These are an example of 4 groups though there can be any number of different groups depending on the strengths of the individual learner.