I think the easiest writing system to learn is the Korean alphabet called 'hangul'. I learned to read it after a long time trying to learn Hiragana. I found Hiragana hard to memorise and decided that Hangul's 24 letters and 27 logical digraphs was much easier. It is read in syllables of 2-4 letters in each block.
I used this youtube video and worksheet with it. After that I quizzed myself on each letter. Then I practiced reading it.
Hangul was invented by King Sejong the Great in 1444 and was described in 1446 in the document 'Hunminjeongeum'. Before that time only members of the highest class were literate and used hanja (Chinese Characters).
Next week: How hard is learning Hiragana?