soft sugar cookies

When I was young I had an aunt who made sugar cookies, that were about 1/2 inch thick about 3 1/2 inches in diameter, and they stayed soft! I have tried her recipes ( yes each time she gave it to me it was different) and can not keep them thick on the edges and make them stay soft-can anyone assist me with this problem? If you contact me at ewaldt_47@yahoo.com I will send you the recipe to review and maybe you can tell me what I am doing wrong. Thank you!