Well, you have a point there, --it is the first step before having a trading activity. You should pick a good exchange first before trading your portfolio there.
I will recommend for the newbie traders is copy trading, there is an exchange platform as of now that has been hacked or scammed, I think people will most likely always doubtful of each other. That bad practice should not increase.

You can choose Binance or Etoro exchange platforms for your trading, it will surely easy for you to understand.