It is essential that whenever it looks like a penny stock is about to fall that you wait for confrmation. This means that you should wait for the stock to fall below a support line on a 5-min chart. You can either short right when it breaks support or wait 10 minutes after it breaks support so you see for sure if it's a fakeout or not. Personally I like waiting after it initially breaks support because I can get a better idea of where the trend is going and avoid getting faked out. Another tip is to wait for the ask price to go below the exact price of the support line price.