If you keep in mind three rules, you won't be wrong.^^/
1.when words end with 'ㄹ', it sounds like /l/ like 물, 입술
2.when 'ㄹ'comes together in a row, it also sounds like /l/ like 걸리다,열리다
3.when followed by vowels, it sounds like /r/ like 드라마,라디오
In my experience, most Chinese feel it difficult when used as patchim.
(A Hongkong friend of mine still pronounces "일요일(i-ryo-iL)-星期天,hari Ahad,Sunday" as "이료이(i-ryo-i)" >,<)
Please check the audio clips out above.
(audio clips from http://www.koreanwikiproject.com)
\^o^/