Besides thinking about what you like to eat, look through lists of vegetables and make space in your garden for something new. You may find a completely new taste experience or an interesting variation on what you normally eat, and have the satisfaction of growing it yourself. This is one of the most fun parts of starting a new garden.
As you plan, consider how the sun hits the garden space. Be careful not to shade ground plants with tall-growing vegetables. (So, for example, place tall plants like corn so they will not shade the zucchini.)
Spaces and Places
Also ask yourself how much of each type of produce you want to have and adjust your planting accordingly. This will affect the total size of your garden as well as how many of each plant you will have. Find out the yield of each plant and how much space each takes in the garden. (e.g., corn grows up and takes less ground; zucchini spreads out. A corn stalk produces fewer ears than a zucchini plant does squash.)
Take into account how the plants are best watered. Some plants need less water than others. Some can be watered with an overhead sprinkler, while others grow better with watering at the roots with canals, soakers, or buried leak cans. The watering requirements of some plants also vary as the vegetables develop. Tomatoes require less water during the final ripening stages to concentrate the flavor in the tomato itself. It's smart to group plants with similar water needs together.
Ways to Plant
Take some time to read about various planting methods. The old "plant ‘em in rows and hills" method is not the only way to go. Try vertical growing methods for tomatoes, melons, or beans. Do wide row planting instead of single-row. Raised beds can be a good solution for lots of things, including if you have difficulty bending and kneeling a lot.
Check the soil for proper pH and amend as needed. Add some organic matter. Fertilize the soil, deciding consciously whether you're going to be an organic gardener as you do. (This applies to dealing with pests as well).