Are there any good suggestions for trading platforms that would be good for starting with small investments? Such as 150$-300$ a month?
To start off, I can say that 150-300$ is a pretty good amount. You can easily be manange to make it around 500$ or so if you choose to invest wisely and if your luck favours.
Moreover the cryptos prices are more volatile, so choose wisely into which currency you want to invest.
I can suggest to you to go to binance or bittrex, as they are the most trusted and reliable site present in the market.
Binance is a really good choice, but I do not recommend Bittrex. They block accounts without explaining the reason. There are many accusations against them, it also happened with me. They blocked me for almost a month without answering my requests.