Low milk supply

With my first daughter I was 18 I could only breast feed about two months but I was starving her due to low milk supply I was heartbroken I had to stop I'm now prego with my second baby and if the same problem happens I want to be able to continue what are things I could do to make sure I have a good milk supply I really want to breast feed as long as I can what are good products for low milk supply any sugesstions thank you