There are some standard adjustments you can make. At 7,000 ft., for each cup of liquid called for in the recipe, increase it by 3 to 4 tablespoons. For each teaspoon of baking powder called for, decrease the amount by 1/4 teaspoon. For each cup of sugar in the recipe, decrease the amount by 1 to 3 tablespoons.

For cakes leavened by egg whites, beat only to a soft peak consistency to keep them from expanding too much as they bake and then collapsing. For both cakes and cookies, lower the oven temperature by 20 degrees or so and slightly shorten the cooking time. You will want to keep the changes on the small side the first time you prepare a recipe, and adjust as needed subsequently.

Unless you give up cooking entirely, you will want to invest in (or rediscover) a pressure cooker, for such things as beans and rice. And despite the wealth of information in this answer, you will probably want to purchase one or more high-altitude-cooking/baking books for a more comprehensive consideration of your question. Among the books currently in print, here are some of our favorites.