Usually they recommend you to diversify your investment, so you avoid losses.
But as a real approach, having $1.5k, would you invest in how many cryptocurrencies ?
What if I invest little by little, only in Bitcoin, would that work as well ?
If you have only $1.5 k I would recommend investing only in bitcoin now.
Why? Because most projects that were hyped in Q2 2018 are now dead with the token price going beyond all the acceptable limits.
Btc seems to be the most stable coin as for now maybe because its popularity as a means of payment for many goods and services.