I've read a few baking books and the general consensus is that some recipes are designed to make crispier cookies, others more chewy cookies. So if you're using a 'crispy" recipe, the most well known is the original Tollhouse your cookies well turn out on the crispier side, but you can reduce that a bit by......using a non-insulated cookie sheet, using parchment paper on your cookie sheet, taking them out of the oven when the edges just look brown and the center still looks a little wet, and then leaving them on the cookie sheet a few minutes before transferring them to a cooling rack...if you move them too soon they'll fall apart since they arent quite "done" yet. Once cooled, you can keep cookies soft by storing them with a slice of bread...the bread gets hard, the cookies stay soft. You also may want to invest in an oven thermometer if you havent already just to make sure your oven is calibrated right especially if you have an older oven.