Hello and welcome, @Sims4sadidles
I'd advise making your own thread/discussion on the topic to get better answers. (But maybe you can't do that as a new member?) Since I'm not sure what exactly you have problems with, I'm going to link you to a few threads with building tips. :smile:
This is probably an overload of information, but this is the collective forum guide to building. Feel free to scroll through and click on the links that you find useful.
https://forums.thesims.com/en_US/discussion/796520/building-tips-and-tutorials-ruthless-kk-build-guide-link-too/p1
I think this in an unlisted thread from the previous that also has a few tips:
https://forums.thesims.com/en_US/discussion/881005/share-your-favorite-building-ideas-and-tips#latest
This is a forum page where a lot of builders gave a rundown on how they like to approach new builds. There's a lot of different ways and everyone likes to start differently, but it casts some insight into how builder's minds work when approaching a house.
https://forums.thesims.com/en_US/discussion/945244/do-you-build-the-exterior-or-interior-first
This is a thread where some builders discussed how they liked to combine items with the MOO (bb.moveobjects) cheat to make new items. Note that a lot of non-builders don't usually appreciate it when you create new furniture.
https://forums.thesims.com/en_US/discussion/945100/here-a-moo-there-a-moo-everywhere-a-moo-moo#latest
Best of luck! Practice makes perfect!