Hi Cynthia,
Classical feng shui is about how you use and harness the Qi in your house, not clogging them with tons of ornaments, jades or crystals. Imagine a friend coming to your house and see your house all covered in those ornaments...will they dare to come again knowing the feng shui is bad? Major shopping centres in Orchard Road and hotels are all feng shui-ed before. Can you see them hanging any ornaments anywhere?
Normally in classical feng shui, the most important part of the house will be the main door, the stove, the bedroom and the bed location and direction within the room. If these 3 are good, generally the feng shui of the house will be good (assuming the external is good). Other factors such as the academic sector, romance sector, wealth sector etc will depend on individual house.
Normally we want the main door to be good. Well, it's true that you cannot change the location of the main door for flats and condos. So if it is bad, we got to see how bad it is. If it is very bad, it could cause serious illness such as cancer etc or even death. In this case, though it is disappointing news, don't you think it is better to know than not to know? Techniques and elemental cures can be used to minimise the effects of these negative Qi. Even if you cannot change, i will be able to advise which year the problem will occur so you have to take extra care etc. There are other methods to "change" the door, but it depends on the type of HDB you buy.
If the door is good, it is not enough. The stove is very important too. Most of the major health issues (such as kidney problems, cancer, urinary tracts problem, liver issues, couples unable to conceive though gynae proves nothing wrong with them etc etc) is the result of the stove sitting and facing the wrong Qi. This can be easily solved by few methods.
Lastly, which bedroom is the best? The master bedroom may not always be the best room as the Qi in every room is different and will tell you what will happen to the occupants staying in that room after some time. So, in Classical Feng Shui, we will identify the best room that will support your endeavours and after which, we need to align the bed location and direction to tap into the best Qi.
Only after all these, then we find your wealth spot to activate it. Note that not all houses can use water feature to activate the wealth spot. Some houses cannot use water and will bring the negative effects! Some houses don't even have a wealth spot.
Of course, the above are the main things to look out for whenever you do a Classical/Authentic Feng Shui audit. There are others such as the academic sector (to boost your study or kids study luck), romance sector (to activate your romance luck if you are single) etc etc to solve a particular problem you are facing.
So, in a Classical Feng Shui audit, a master will not just say "your house is good" or "your house is bad" or "your house should paint this and that colors". This is very superficial and easy. You should ask "WHY" in everything he ask you to do. Only by knowing WHY will you understand and knowing the logic and basis of everything he ask you to do. Personally, I love clients to ask questions. Nothing constitutes a silly question. It's either you know, or you don't know. I always explain to all my clients what specifically will happen to the occupants of the house after staying there for some time. The main door will cause certain events to happen. Occupants staying in different room will also experience different events (good or bad depends on the Qi in the room).
So to answer your question, I normally try to minimise renovating and hacking unless really necessary. Most of the time, you don't need to, unless the house has really very bad feng shui, which in this case, you have to. Unfortunately, putting 1000 crystals will not solve the problem!
Hope this answers your question Cynthia