I was just going over my mods reference doc earlier today adding links so I'll add some more to the mix. I've listed my favorite creators and links to their pages on multiple sites. Most sites can be viewed without signing in, but you will have to register and be signed in to view TFM's Naughty Sims Asylum and maybe Simlogical and the Dead End Nights.
I use multiple mods for most modders. NRaas are the ones I have the most of.
alverdine @ MTS
http://sims3.modthesims.info/member.php?u=6989003
Ani @ MTS
http://sims3.modthesims.info/member.php?u=3002461
bluegenjutsu @ TFM's Naughty Sims Asylum
http://simsasylum.com/tfm/
Buzzler @ MTS
http://sims3.modthesims.info/member.php?u=432522
icarus_allsorts @ MTS
http://sims3.modthesims.info/member.php?u=7081784
Inge Jones @ Simlogical and the Dead End Nights
http://www.den.simlogical.com/denforum/index.php?board=15.0
Jynx - Rabbit Hole Rugs and Doors are now being hosted on Misty's site
http://simsl3gacies.com/blog/2014/06/15/jynx-rabbit-hole-rugs-for-base-game-and-late-night/
Misty
http://simsl3gacies.com/blog/category/sims-3/
Margaret Pendragon @ MTS
http://sims3.modthesims.info/member.php?u=3789023
NonaMena @ MTS
http://sims3.modthesims.info/member.php?u=4938621
Nona's Sims @ wordpress
http://nonasims.wordpress.com/
Nona's Wiki
http://nonasims.wikispaces.com/
Nona's Nook @ Simlogical and the Dead End Nights
http://www.den.simlogical.com/denforum/index.php?board=54.0
NRaas Wiki
http://nraas.wikispaces.com/
sydserious @ Simlogical and the Dead End Nights
http://www.den.simlogical.com/denforum/index.php?topic=3026.0
Twoftmama @ TFM's Naughty Sims Asylum
http://simsasylum.com/tfm/
Shimrod @ MTS
http://sims3.modthesims.info/member.php?u=3066089
Shimrod @ TFM's Naughty Sims Asylum
TS3 and TSM
http://simsasylum.com/tfm/index.php?/forum/221-shimrods-mods/
velocitygrass @ MTS
http://sims3.modthesims.info/member.php?u=3045250
It took me a while after starting to play Sims 3 before I started using mods. Now I refuse to play without many of them. Depending on game-play, I'll remove a mod or mods from my folder and tuck it away in a folder on my other drive. I don't use all of them in every game.
You can easily add and remove mods, but you should always remember to clear your scriptCache.package file before/after adding and removing. It's good to save links to the mods you use to make sure that the ones you are using are up to date. Sometimes the creator will tweak a mod to improve it in addition to updating for new a new patch (if needed).
Edit to add: You do not have to be signed in at Simlogical and the Dead End Nights to access the pages.