I would start with bitcoin, more resources available for you to learn and a nice buying point today
No matters you start with any coin or either it us ethereum or bitcoin. I think you first have to buy bitcoin and than you have to exchange it into any coin you wants. Buy bitcoin first because trading is good when you dealing with volatile assets and I think bitcoin would be a good start for trading and make a decent day to day profit, Ethereum is on the stable side of the market but it's been showing good signs now, just put it on your watch list.
There is a famous quotation that Its better to be master of one than to be a jack of all, in the business of crypto currency, you can take advantage of everything and this quotation can be proved wrong. You can earn a very good money with a single currency or by investing in all the currencies, But if you want to stand out and make some difference in the trading than my opinion is to master in bitcoin and rock the market with your calculations.