Trees: the absolute hands-down best way to add value is by planting trees. Give thoughtful consideration to placement, taking into account how large the tree and its branches will get at maturity and an understanding of the spread of its root system.
Trees don't depreciate.
Front Walkway: spend a little effort on your home's 'first impression' and you'll be greatly rewarded. An entrance that is clean and well-decorated sets the tone for overall quality of the entire outdoor environment.
Landscape lighting: enhances security and instantly lifts the overall look of the home.
Create Privacy: a sense of privacy is important to generally everybody especially when at home. Clever use of trees, shrubs, and grasses can achieve this.
Add Fire: firepits are extremely popular for a reason. They create a sense of warmth and coziness not to mention ambiance in any home's yard. It is a universally beloved outdoor feature.
Install a quality irrigation system: worth its weight in gold to every homeowner. Saves time and water and reduces watering bills. It has a return on investment of 85%.
Consider earth-friendly, drought-tolerant landscaping: a landscape with less maintenance and less cost.