For trading try to use those places where you are aware or one of your friend or family member have experience on there because anyone can create an exchange and can scam you. One of my friend started trade on a new exchange and on there she lost a half bitcoin when they created a hack drama and announced that they cannot pay the users and exit their site. That was my suggestion to you and other crypto users.

For Okex I will say that it is a good exchange and I have traded on there and not found any issue there. You can trade there you may also not find any issue there but whenever you will like to try a new exchange try to do full research about that exchange first and read all reviews about that exchange on google.