Actually, It depends on how much time you have for preparation.
I'm going to take the IELTS test next July, so i don't have that much time.
For the speaking part, currently I'm taking some intensive English sessions through italki.
I also have a very long list of new words that I must memorize so I can use them in both speaking and writing.
Watching English shows and movies had helped magnificently in developing my listening skill.
Anyways, if you have a short time like me, the best thing to do is to bring some IELTS tests samples and test yourself. The more tests you do the better your skills will get.