There are some basic considerations. Many landscapers, to increase revenues, place plants too close together. They look great now but when they mature, they crowd each other. Do some research and imagine what your landscape will look like when the plants mature. Avoid invasive ground covers near your home.
Most gardeners enjoy over planting perennials.
However, if you don't divide these every few years, they may become overcrowded. For less maintenance, leave more space between perennials and fill the spaces with annuals. After thinking about types of plants and developing a plant list, plot your master plan with pencil and paper. To see your plan, it's helpful to use a limber hose to lay out any new curves in your beds. Curves are better visually than sharp edges and easier to mow.