Like what the majority of people here have said, going with what the existing community agree's on as trusted is a good start.
I personally started with Kraken, then branched out to Gdax/Coinbase, and Binance, to this day I've not had any problems with any of those three.

This wont really help you, but it is important information for the crypto-newbies, regardless of the popularity of the exchange you are looking into, there seems to always be some negative comments, with some exchanges being extremely polarizing, so it is important to do your own research into whatever exchange you wish to use.

I like to use the exchange section of CryptoCompare to read up on some exchanges, link is here