Best to start with some smaller and simple mods just to test the waters if you're feeling it with them.
As per usual when you download something, always do a virus scan on them. Always best to download mods from their sources and not any 3rd party sites (Simsdom, etc.)
I tend to not use super big mods that have a lot of gameplay (like Sacrifical's mods when there's a patch update they tend to break until updated or they just bug pretty bad cause they have so much going on).
There is a chance some mods might conflict with one another. Like you don't want two mods in your game that do the same thing so you'd want to just keep one.
Bienchen does a lot of my favorite small mods and frequents the forums here.
https://deichschafblog.de/bienchen/
LittlemsSam also does a lot of small mods as well you might like.
https://littlemssam.tumblr.com/post/175435360448/mod-overview-list
MC command center probably the most used mod by many. Bit of a jack of all trades. Since you can do so much with it (bump up the cap for how many sims are around on a lot, so getting inheritance when someone dies, have bills higher or lower) and is user friendly at that. Not to mention there's a step by step document to tell you what does what as well.
https://deaderpool-mccc.com/#/releases
Here's a guide by Carl about installing Mods and CC
https://www.youtube.com/watch?v=C0TRT_aj8H0