Hey I'm new to that crypto game and wanna make some money

Have bought into BTC and have sent it to bitfinex now and wan't to start trading and investing later.
A friend of me who is in the game for while told me that almost all coins are crap and I should hold only BTC and maybe Monero but not now because prices are still too high.
I'm thinking now about to short Ripple, IOTA, Litecoin and Ethereum.
So my question is what is the most worthless shitcoin that make me the most money with shorting and how low can it go?
I do not think it's worth investing in Ripple now. IOTA is a good project, I also plan to invest in this coin in the future. Now the price for all coins is low, so you can invest in any promising coin.