When you light your first fire, fill the basket with coal, do this every time. Light a small amount, like one or two coals, set your bottom vent about 1/2" open, and top vent about two turns, lid closed. As your temp starts to approach desired temp, start closing the top. There are many techniques to do this, you may develop your own, but this is a start. Primarily, newbies often light too much coal to start, and it's difficult to impossible to bring a temp down.
Robert