If you are making a Zen rock garden, clear the grass off of a spot where you want it as large as you want it. Rake it until very smooth, then pour as many bags of sand as is necessary to get 2 inches of sand. Rake the sand with a metal rake to form ridges. It is most effective when highly ridged. Place rocks or small boulders where you like, but avoid too many one or two is enough. Rake as often as you like to meditate.
A flower rock garden is nice on a gently sloping hill. About 40 ft long by 25 ft across is nice if you have the space. If you don't have any existing trees, you will have a long wait to get the full beauty that comes from a few trees in strategic spots. Magnolia is nice, Rock elm or ulmas thomasii will be beautiful but susceptible to Dutch elm disease, dwarf fruit trees are a best choice for new plantings to get a nice effect quickly as are Japanese maples. Wild cherry trees are great if you prune them into nice shapes. Once you have the trees where you like, place the rocks, boulders, garden elves (lol), wrought iron nick knacks, statues, or whatever your heart desires in your garden. Then decide what plants you want to display. Decide first by water requirements, how much shade or sun is necessary in accordance with what you have, then color, then by height, then by length of flowering if you choose flowers, and you always need to consider how much work you want to put out in maintaining it. Ferns and ground covers need little after care, while lots of choices need twice daily care. Pyracantha and Japanese holly make nice specimens if you lop and shape them often and they provide food for winter birds too. That's my 2 cents on the subject.