Decide what you want to accomplish with your rock. Consider what type of rocks will produce the look and feel you desire and what combinations work best together. Does one style of rock match the style of your home and other plants and decorations better than another? Find the right rocks. If you are lucky enough to live in a rural area, you can probably find some attractive and useful rocks for free---particularly if you want to build structures like a wall or fire pit. Nurseries, garden stores and home improvement outlets sell a wide variety of decorative stones---from pebbles and pavers to cobblestone and flagstone. Some interesting places to start looking for the perfect rocks are listed in the Resources section below.
Balance the placement of your rocks to reflect a feel of permanence---as if the rocks have been in place for years and not just haphazardly thrown on the ground. Do this by planning carefully where you want each rock to sit and what purpose you want it to serve. Avoid placing your stones at exactly measured distances, as this usually looks "forced" and unnatural. Place the stones in areas that add to the yard without looking like they are covering something up or begging for attention. Rocks are yard and garden accents, not features.
After you have your rocks in place, take time to bury each one 4 to 6 inches in the ground---burying the larger stones furthest down. After each rock is in place, simply pack the dirt back around its bottom and rearrange the ground cover as naturally as possible. This not only makes the stone look like a permanent fixture of the property, it adds a bit of mystery to it, because no one knows how large it actually is. If you are planning on building any stone structures, such as a retaining wall or a bench, be sure to lay the rocks with the flattest tops down first to allow easier stacking.
Building options are limitless when dealing with garden rocks, but the most common structures--retaining walls--are usually either fortified and mortared long-term walls (often over 4 feet in height) or smaller dry-stacked garden walls. Larger walls require the building of bottom support bases and concrete mortar between the rocks. Smaller dry-stack walls can also utilize a natural mortar--like common yard soil--to help solidify the structure and add a more permanent look. Large gaps between the rocks can easily be filled with the soil mortar, not only to reinforce the structure, but also to allow the planting of ground cover that will grow naturally from the wall. Tips on building walls can be found in the Resources section below.