The most common landscape design mistakes are ignoring mature plant size, skipping a plan and buying plants one trip at a time, and scattering small beds and features with nothing tying them together. Planting too close to the house is the classic: a cute 3-gallon shrub becomes a 12-foot wall blocking the windows in five years.
Other frequent ones: undersized patios (a dining patio needs roughly 12 by 12 feet for a table and chairs), no focal point, ignoring drainage until water sits against the foundation, and choosing plants for the nursery tag instead of your hardiness zone and sun exposure.
Almost all of these trace back to deciding at the store instead of deciding on paper. Working from a photo of your own yard with AI landscape design makes the plan-first habit easy.