I lost my earned profits, went back to where I started. What should I do?

I am new to trading and stock market. Yesterday, I lost almost all my profits. So far, my stategy has been when I see the stocks going down, I would enter at low price and the next day, the stock prices would go up. I have won in my initial 4 trades and raised my initial 300$ to 350$. On my last buy, I saw SOUN was down and I bought it thinking it would go up the next day. But all market crashed and I lost 40$, almost all my profits What can I do? Is my strategy bad? Please, I am open to any suggestions. I know it is not a huge sum and even I still on the possitive but I don't want to make this mistake again. P.S. I live in Caucasus and my salary is around 600$ so it was huge loss for me for the context.