Almost all vegetables and most flowers need 6-8 hours of full sun each day. So you need to observe your yard throughout the day to figure out which spots receive full sun versus partial or full shade.
2. Pick the Correct Spot
Don't worry if your lot is mostly shady: You won’t be able to grow tomatoes in shade, but many other plants (such as hostas and outdoor ferns) love it. Don't skip this step, because in order to thrive, your plants need to have their light requirements met. Check plant tags or ask the staff at your local garden center to help you understand out how much sun a plant needs.
Three additional tips: Pick a relatively flat spot for your garden because it’s more difficult, time-consuming, and expensive to deal with a sloping garden. Check for windbreaks (such as your house or your neighbor’s house) that will keep plants from being harmed by strong winds. And put the garden where you can't ignore its pleas for attention: Outside the back door, near the mailbox, or by the window you gaze through while you're cooking. Bonus if that place is close enough to a water spigot that you won't have to drag a hose across the entire yard.