What is the best lot size for $30?

Could you please explain, what exactly do you mean by "lot size" in the context of $30? Are you referring to trading cryptocurrencies or some other financial instrument? If it's trading, which platform or exchange are you using? Lot size typically refers to the quantity of a particular asset being traded, and it can vary depending on the platform, the asset, and the trader's risk tolerance. Given the small amount of $30, it seems unlikely that this would be a sufficient amount for any significant trading activity. Could you clarify your question further, or provide more context so that I can better answer your inquiry?