Let's talk about the grammar first.I don't think it is the most important thing to remember some grammar by rote,actually the literary sense is what we should emphasize most.But how can we obtain the inerrant literary sense?Just read more.
Here we come to the second item-reading.Reading skills are improved while you scan the magazines,newspapers and everything you like.For further help you can refer to your teacher.Just read more,overcome any difficulties.
Then,the spelling.Unfortunately,it is also the weak point of mine,I just want to say reading and writing from memory must help.
In one word,learning English requires a lot of work,I think the most important one is to do reading,which can benefit every aspect of your English ability,especially your literary sense.
Thank you.