What should I be doing with my preschooler?

Many parents with young children ask, "What should my child know before starting kindergarten?" or "What should we be doing now?"
Here are some helpful skills for the under-six crowd, in approximate order of importance:
Independent toileting, including good hand-washing;
Using good manners, especially with regard to keeping one's hands to oneself and sharing objects;
Following simple directions;
Recognizing and avoiding hazards (e.g., putting away an item that could be tripped on), and observing one's environment in general;
Waiting quietly for a moment while the teacher pays attention to someone else;
Listening to a story and talking about what happened;
Being aware of time and routines (not necessarily telling time);
Putting things back where they belong when finished with them;
Putting on one's own coat, shoes, hat, etc.;
Expressing choices and preferences;
Playing cooperatively with other children;
Eating and appreciating nutritious foods, preferably with a willingness to try new things;
Recognizing basic shapes and colors;
Using/manipulating classroom objects (such as crayons and blunt scissors);
Recognizing letters, especially one's own name, and saying/singing the alphabet;
Recognizing numbers and counting to ten;
Categorizing items (by size, shape, color, etc.).

Beyond that, enriching experiences are great. If you can take your child to the beach, the forest, a big city, a farm, and so on, these activities will provide background knowledge that gives him or her context for stories as well as subject-area learning. But there's a lot you can do in your own home! Cook together. Plant some seeds and see what happens. Ask your child to predict what happens next in familiar and unfamiliar situations. Talk about the reasons behind some of the choices you make. Cuddle up and read library books on a rainy day.