Then you'll be pleased with your successes rather than disappointed with your attempts. Also, try something new, if just for novelty. You'll automatically include the veggies and posies you know your family will enjoy, but adding something new will give you a new adventure. Purchase those that are known to do well in your immediate area. Even then, a particular vegetable or flower variety may produce well for you but not for a friend a few miles away or across town, and vice versa.
Gardening can be either frustratingly uncertain or an exciting challenge.
Each gardener gardens differently, according to his or her own needs and desires. Soils differ in proportions of sand, silt, clay, and organic matter. Weather seems to never be consistent from year to year. There's always something new on the market to try as the perfect vegetable or flower or tool or technique. The great fun is in discovering and making the perfect garden happen.