One of the easiest mistakes homeowners can make in their lawn or garden is not anticipating the eventual size of a plant. Most of the plants you buy at the nursery will be labeled to tell you what their mature size will be. Believe it. In fact, most labels will give conservative specifications so give yourself a bit of room even beyond what they describe.
Also consider that what is in full sun now may be shaded when that tree you planted reaches maturity. Remember, it definitely helps to plan ahead.