Where can I buy penny cryptocurrencies?

Good day, I'm interested in diversifying my crypto investments and I've heard about penny cryptocurrencies as a potential avenue. However, I'm not quite sure where to begin my search. Could you please enlighten me on the best platforms or exchanges where I could find and purchase these penny cryptos? Additionally, are there any specific factors I should consider before investing in such low-valued cryptocurrencies, such as liquidity, trading volume, or the reputation of the exchange? I'd appreciate your insights as a professional practitioner in the field of cryptocurrency and finance.