In my opinion, to get great aquascapeing you first need to do at least some planning. You need to have some idea about what your trying to do.
Also in my opinion, the type of tank makes a big difference. I sort of hate to say this, but FO and FOWLR tanks look rather dull next to a reef. Not that FO or FOWLR tanks are going to look bad, and depending upon the fish being kept might be required, but for pure aquascapeing a reef system, because of the live corals and related livestock is the system of choice.
Great aquascapeing will include fish, but the main emphasis is on the aquascape, not the fish.
Tank shape does matter. It's extremely difficult to get a decent aquascape out of a comparatively narrow tank such as a 55 gal, since it's only 13" front to back. A wider tank or cube will let you do more. Personally, while a lot of people love them, I just can get excited about bow front, wave front, hex, and similar tanks. I find that these tank shapes look interesting, but do a far worse job in showing off the aquascape, which I feel is the main attraction. I'm not saying you can't do a great aquascape with one, but it's tough.
As for "... walls and pillars, caves, laced arches etc. ..." they need to fit together so they look like something your see out in the wild. For example, making a single cave right in the center of the aquascape looks very artificial, but a series of interconnected caves through the aquascape will look great. Other things that I find that makes an aquascape instantly fail are a pile of rocks in the center, or a rock wall that goes top to bottom and left to right. Another almost instant fail is a design that is completely symmetrical.
Consider that the live rock, along with any hidden structure, is the supporting structure for your tank. The corals that are going to grow on it need to look like they always lived there. They are going to take some time to grow in. You may have noticed that the really fantastic systems have been set up for years, and have had time for livestock to grow in. This can take a long time with LPS or SPS corals.
Lastly, keep in mind that this post is my opinion of what I like and don't like. Everyone is welcome to disagree, since an aquascape is very much a matter of personal taste. You might love a look that I'd never even consider for myself. That's OK.