Mostly I will simply start with the exchange which are being subscribed by the devs of one token or coin. I mean I will look into their ANN topic or their web site for the list of exchanges where I am able to trade their coin or token. Then I will register and then move my tokens and then I will convert into bitcoins or ethereum and finally I may forget that exchange until coinmarketcap kind of summary services notifying the same exchange for another coin selling purposes.

I am not an active trader hence I am not taking much time to analyze and to choose exchanges. Always for first trade with a new exchange, I will risk small amount only. This is only my precautious approach for a new exchange.