Before choosing an exchange one must carefully look at the security features of an exchange and its reliability.

It really depends on what you are interested in when chosing a cryptocurrency exchange. Factors to consider include:
Price: cryptocurrency prices between exchanges may vary a lot.
Fees: some cryptocurrency exchanges have very low prices and fees when trading.
Security: security is also an important factor when chosing an exchange, especially if you want to leave your Bitcoins on an exchange.
some exchanges might not be available in your country.

Hope the suggestions above helps you out as you continue your trading adventure!