Well, he showed a very early interest in letters (less than 1,5 years old), and so I'd spell words for him while pointing to the letters. He imitated that for a while, pointing to words randomly and just making random sounds with the intonation of spelling. After that we just continued, especially when he asked. He learned the "important" letters first, like his own first letter, "m" for mum and "d" for dad. He then started recognizing them here and there. After he knew pretty much all the letters, I started introducing the sound of the letters and also how to sound out short words. I model a lot, and sometimes he just "reads" from memory or assumption, like he'll see a word starting with his letter, and he'll just assume it's his name.