It's really going to depend on what LPS or softies you have, there's no one answer. Have to take in account for tank height, lighting, flow and direct or indirect lighting. The best thing you can do before you purchase any coral is research what their demands are.
I always start at the bottom and and slowly move them around to where I would like them. Just because I would like them in a particular place does not mean they will like it there.IMO it is more of a trial an error thing, Good luck
I start everything in my sand bed and go up from there a few inches at a time, every few days. If your coral reacts poorly (doesn't open, loses color, etc.) move it back to where it was and try somewhere else until you and it are happy.
Keep in mind flow plays a part as well. If you stick a candy cane right in front of the stream off a power head it might not do as well.
I do the same as Tony & Jeff. I start out on the sandbed and slowly work my way up. I usually give corals a few weeks on the sand bed, and let them settle in/ get acclimated to my tank's lighting, then start moving them.
You should always start at the sand regardless of the type of coral. Many, if not most, LFS tanks are somewhat dim, as are the wholesalers/distributors tanks. Corals, even high-light intensity corals, adjust to this level, and immediately placing them under very bright light can actually bleach them.
So you want to start at the sandbed and work your way up depending on the light needs of the coral.
Starting from the bottom is always better than starting from the top, though do be a bit flexible with your codes of conduct. And be very careful when using websites such as LiveAquaria as guides to place corals. Those websites are good starting points, but make sure you do a lot of research and rely on the more scientific sources.
For example, I found that Sinuous Bubble Corals (Plerogyra sinuosa) can do great in low or high lighting (not just medium as LiveAquaria suggests). The thing is to be aware that Bubbles for example, exist in both depth and shallows in the wild, however only those in the shallows have anti-UV factors that help protect them against the sun's rays. Putting them in direct light will do them no harm, but putting specimens from the dark in direct light can be very bad. Although the converse is not true.
So yeah, it is horribly confusing, though the above do suggest what has already been mentioned - start low, go high.