How do Ты come up with an anime/manga story line?

I write my own Манга too! :D ... and... Well, i came up with some story lines while sleeping O_o ... And i think of some new ideas totaly randomly and i always write them down ASAP... So... i don't really think there is a "best way" to come up with a story, it just randomly comes... Also Ты could find a good idea just from your everyday :) (And Ты can change that into any genre Ты want)

I draw my own Манга for fun so I am no professional at all; but Ты come up with a storyline just as Ты would with a book или any other story. As Манга is often serialized, however, it's best to have a storyline that can span for quite some time without the reader getting bored. Sub-plots are essential.