Where to find Mods
Mods are usually available on the creator's individual site, however, you can find some on Mod The Sims or other CC finds sites. YouTube is also a really good place to find recent mod reviews.
How to download for success!
Always make sure you are downloading the most recent version! If you are not running an updated version of the mod OR game, the mod likely will not work.
Modders will usually denote if their mod works with the legacy edition - or you can reach out and ask!
READ THE INSTRUCTIONS! As boring as it sounds, you should fully understand the mod and how to install it before you add it to your game. The instructions will typically include other required mods, items, and packs for the mod to function as expected. They will also include if certain modules can be removed and any add-ons to increase gameplay. READ THE INSTRUCTIONS!! I cannot stress it enough.
Downloading mods is generally safe, as long as you download from reputable sites and don't click on any ads. I have never had any issues with downloading mods, however, download at your own risk. EA is not responsible if you download something that corrupts your game or hardware.
It is always safest to download directly from the creator's site, whether it be Tumblr, SimFileShare or Patreon.
Do not click on any ads or pop-ups. Tips to avoid adfly at the bottom of the page.
Make sure you have some anti-virus measures in place. Most computers have a basic one that should suffice.
Stay away from sketchy sounding mods and sites. If in doubt, exit out.