Practice, practice, practice....
You need exposure to English, which is difficult in Malaysia where you are surrounded by Bahasa Malayu, or at best Manglish. Moving to Singapore won't help as Singlish is little more than a creole, and KL is more fun anyway!
Try this website -> BBC Learning English | Bolivia proposes ban on the word 'coca'
where you can listen to beautiful English, and read the story at the same time.
This site -> Churchill House School of English Language courses England UK has grammar exercises to brush up your grammar.
Both of these can be found through www.infernolanguage.com, which also has some word games you might find useful.
Other strategies are to watch BBC World on your TV, listen to it on the radio (probably 88.9, it is here in Singapore), watch English movies without using the subtitles, and maybe listen to English songs - 'Sunscreen' is a good one. If you Google it you should find a free download, plus a lyric sheet. I managed to!