I would suggest you to register into as many exchanges as possible - you will need those sooner or later as some very interesting coins are only on small exchanges...Start with Binance (buy some BNB tokens there to lower your transactions fees to 50% + I think BNB is a very good investment opportunity) and also register ad Huobi, Kucoin, Bittrex, Cryptopia.
For newbies I think Idex trading is a part of the deal. market or forkdelta and etherdelta. This will be a great learning experience and the fees are quite low for these places. Do not go to the big floors that will make it difficult for him and may encounter high transaction costs.