I can't call myself much of a builder as my app got denied but I do know some basics, if you want to start building I would recommend you to check first of all building tutorials for some time, there are very good people at it out there such as grian who isnt exactly a big scale style but shows a lot of the basics so you can develop your own style.
Another important point I would recommend you is to look for buildings other people has made and learn how they made them, that is not to copy but to learn the techniques used and add them into your repertoir.
But the most important part is to build and use all the new things you learn not stopping that process (well maybe to rest).
After you have been going for some time you can go to the next level and start using programs such as world edit and voxel sniper for the heavy work, spritecraft is very usefull for blueprints or many more.
I can't tell you anything else more about what goes next because this is the point wwhere I am so I guess you can ask luke, fongus or any of the builders...I guess