For the novice gardener just starting out I recommend taking one step at time. Start with what you currently eat. What are the things you find yourself purchasing regularly? Lettuce, green beans, tomatoes? Take a minute to write down what you find yourself purchasing already and go from there.
Once we know what we like to eat, look at what you are willing to eat. Sometimes the veggies we routinely buy aren't well suited for our gardening area. I live in the deep south so crisp head lettuces are not practical for my gardening climate, but I am willing to eat leaf or soft head varieties like Mesclun or Buttercrunch. English cucumbers are long and tasty, but they tend to grow bitter for me in my garden so I change out little munchers instead. Look at what you are willing to change on when it comes to practical productivity.
Amount. Take a minute to consider how many you intend to feed, or if this is a hobby garden. I am a canner so my garden is intended to be bountiful. Mine is intended to feed my household both in season and out and be productive enough to share with others.
Another consideration is time and space. Some garden crops are time consuming to upkeep..needing heavy feeding, trellising or routine pruning. Do you have time to fertilize every couple of weeks for plump sweet corn? Do you have the space to grow potatoes? Carrots are seriously slow growing and will take up garden space while you wait for them. Some crops are more cost effective for a small garden grower because space and time in the space is just not practical.
What about me personally? I get a lot of questions about what I grow routinely in my garden. First let me say, I have three large garden plots on my homestead; they rotate seasonally. One entire garden is based on a herbal tea set up containing culinary herbs, medicinal herbs, and roses. An entire garden is set aside for the traditional 'Three Sisters Garden'. Here sweet corn grows and provides a trellis for runner beans while melon vines trail under their feet. Grown in succession, once harvested the section is sown in cover crop and left to rest until the next cycle. A traditional plot grows in the third plot in spring and fall. Set up in the 'Victory Garden' style this garden hold cole crops (broccoli, cabbage, cauliflower), leafy greens (lettuce, kale, chard, spinach) onions and roots (carrot, potato) until summer when cucumbers/squash, beans, peppers and tomatoes take their place.
Are you a new gardener? Consider getting in touch with your local extension office for a list of recommended plants for your area. They have excellent lists readily available for you. The soil is calling, lets get growing.