Very simply @sparky0347, as one pencil guy to another, modding your sim is as much an adventure as flying.
While there are thousands of add-ons available and the list will just continue to grow, I suggest stepping off that precipice from the lowest level first. Download ONE thing that interests you and mess about with that. Learn how the community folder, official folder, market place, etc. work. There is a program called “Add On Linker”. Start there. It will take much of the guess work out. Understand that some of those add-ons are going to have their own installer. Some are going to require that you use that installer to uninstall as well.
In reality it is seldom the base that creates a problem. Users that are mucking about with config flies, mods and system settings are usually the most likely cause. There are bugs in the base but most turn up because of an incompatibility or conflict somewhere.
Proceed slowly. Be wary of every download. Test the hell out of every add before adding something else. Modding can be rewarding. It can be easy. You can add 1000’s of mods and never have a problem. You can add one and spend the next month trying to figure out why your friends are getting strange emails from you.
This is a complex software. Lots of ways to screw things up. You will, however, never learn if you don’t mess about. Just be diligent about it.