Seabody, I'm not good builder in aestetic way such are those you mention in the begining, but I do have something to add.
There is a huge difference between practical and functional houses and those that are beautifull to look at but not so easy to play with. Builders you mention are great in both, but they are both talented and informed and have years of practice behind, so don't try to immediatelly recreate one of their masterpieces.
I don't like huge rooms, and when it takes Sim hour to get from bedroom to the kitchen. Also, huge rooms always look empty so I tried to learn building practical homes, using space to have everything functional and easily accessed and to have a nice look at it while playing it. That is why I never put trees next to the house - it block the view when you play. I also rarely buy only decorative objects and those I don't really use (I do the same in RL hehehe).
take the advice you get, to study around real homes to see what is where and try to understand why. Next one very important is what danefaith told you, try learning what is belonging to what style - that is making huge difference when you build. Also, try to have the idea what you want to build when you start - modern home, cottage, boungalow or mansion.
I usualy build one room at the time, and add/remove walls as needed. Start with whatever you have the best idea what will look like. For example, when I was building this mansion I started with pool area and pond because I knew how I want it to look like, and then start with building house starting with entrance and stairs. Then tried to get the simetrical look with living area on one side, and private areas on other(bedrooms):
Back view:
Front view:
With this one I start with kitchen and dinning area, add the entrance and stairs, then bedrooms on second floor. Again, looking for simetry (which is not modern style).
(not really masterpiece but it is not ugly looking to me at least and is very very functional with everything 4 Sims need, plus it is not expencive)
This one was different because I had to start with underground area for aquarium, so I had to use above space respectively:
That didn't turn out well cause I made huge square of fondation and build from there, instead from actual parts of future house.
If you're not planing to upload houses to Swap Shop for someone request, I guess the best goal should be to make a house that you like to play with, evene if it doesn't look amazing to everyone. Playing with different patterns, using ALT and moveobjects on you can arrange furniture in unusual way, and using your favorite color and theme will make you happier to play with.