To improve your vocabulary, read Reader's Digest. It is a very
powerful vocabulary improver. I read it once and was stunned i
managed to learn words that seemed bombastic to me in the past.
For grammar, read newspaper, novels and magazines. When i say
read, you actually silently read out the words to yourself. Moving
your tongue will do, no need sound effect.
Please do not read tabloid newspapers, novel and magazines. They
are full of 'unwanted' contents that will tarnish your command of
any language you want to learn or improve. For me, i read National
Geographic, Straits Times.
Oh yes, to improve further, write. This is very simple--Try
writing compositions or essays about the things around you. This
will be very easy for you, i believe.
As you write, read to yourself again. This will reinforce the
usage of the language. Do not use bombastic terms unless you really
know them. Try explaining it in simple terms--your readers will
understand what you are saying.
Last but not least, record yourself when you are pronuncing some
words. From there, you will know how to pronuce the words
Keep up the effort and inspire those like you