I'm not a genius when it comes to trading crypto so I started on Coinbase. The transaction fees were way too high so I switched to Binance because it's in the top used platforms of all others. There is a big learning curve with all the tabs and types of transactions that can be done but it gives so many options to trade crypto. Nothing a quick google search can't help you out with.
Binance offers a lot of information on crytpo like education and graphs as well as a crypto wallet to store coins.
This platform seems to be quite safe with the ability to use Google Authenticator and about 5 other ways to verify your account.
Personally, I had trouble adding a credit card but the customer support was able to help.
If you're into Alt coins this is the platform for you.