If you have your heart set on growing a specific plant, check to see what growing conditions it requires. Vegetables will need at least 6 hours of sun exposure a day. The same goes for most flowering plants, however there are still many to choose from for a partially shaded site. If you want to start a garden where there is mostly shade, your choices are going to be more limited, but not prohibitive.
The folks in this picture have a partially shaded front entrance. They could easily add a small garden along the walkway where they could enjoy it, making their entrance more of a focal point.
Also take into consideration when the sun hits your site. Afternoon sun will be hotter and more drying than morning sun. Many plants turn their faces toward the sun, so if your view of the garden is from a west window, your flowers may face away from you in the afternoon. Evaluate other elements of exposure such as high, drying winds or heavy foot traffic.
Once you know where you'd like to try your first garden, use a hose or extension cord to try laying it out on the ground.