Where can you get cool but safe mods for Minecraft?

It should definitely be safe.

Here I get my mods:

https://www.curseforge.com/...ft/mc-mods

The easiest and safest are mod packs from the ftb or tekkit launcher

Twitch Launcher, you can easily find all the mods you want from a huge library. Of course free and 100% safe, and super easy.

And he also has a huge selection of modpacks, including all ftb titles.