For plasmids, we recommend the use of commercially available plasmid mini scale preparation kits employing spin columns. From our experience, repeating the washing step will improve the quality of the DNA and therefore improve the sequencing results. Please do not send DNA prepared with alkaline lysis methods or with the boiling method (Holmes and Quigley, 1981) without column purification. For PCR products please use commercially available PCR purification spin column kits.