in short run, I would like to suggest as following :
reading --> read notes / powerpoint / textbook (the best) prior class
(try to guess what does it say ?)
listening --> if do above, maybe more clear what lecture says on class
wirting --> try to memory it point by point
oral --> try to speak more (try to ask lecture for any unclear points, surely u can write it down first)
But be honestly, I believe that there is no short cut way to improve any language. So in long run, i also suggest as following :
reading -- grammar + vocabulary + reading more books (u can start from children's story book that just few pages)
listening -- watching TV / listening radio / communication with others
writing -- write more & read more idioms, good article such as news
oral -- speak more
The most important point is :
understand --> memories --> practice
so all above need is "TIME" + "EFFORT".
Hope above can help..
