Comment by pineapplejuice

My tip is to keep a dict of all the fields and the data types you expect them to be, particularly strings. In my company we have IDs that start with zeros, or are a mix of numbers and letters, and get interpreted as numeric types. I'm frequently pulling data out of the DW with the same fields, so I just have to use the dtype= arg point it to my dict and it takes care of that for me.