I've learned reading and writing in Korean by myself.
I just printed out a copy of korean alphabets,
familiarized myself on how these characters should be put together (through a sample of korean sentences/paragraph etc) ,
learned how to pronounce each character -through the internet, and singing and listening to korean songs also helped me (with a copy of romanized lyrics actually) so more words to try writing in korean. .and also watching korean dramas/shows.
actually the romanization isn't really the same when it's in korean. example: we say Lee, but in korean it's "ee". and they write the way they say the word. r and l, ..b, p and m, they could be confusing (to me.) 'coz (i think) they mix up.lol. especially the "r and l" sound..and in english it couldn't be like that.
i just practiced and practiced . there were times i did learn it in school- yeah when bored at class, i scribble some things in korean.
It's just motivation for me. It started in me when i was hooked on Kpop back since 2008, then i tried copying the names of my favorite singers in their korean characters.and then it lead me to studying korean language. lol that motivated me enough. it can't be that hard if you're enjoying it.