Curse you guys! I'm downloading almost every mod from the Nexus' top list that enhances or expands the game in a lore-friendly way. So much for my "I first want to play the game without mods" statement. :|
I just hope the game doesn't break.
Your game probably will if you just install almost everything on the top list. Sorry. Many mods conflict with each other in subtle or non-subtle ways, and mods with scripts can't even be safely uninstalled. That's not to say that modding Skyrim is bad, it's just that you should be careful what you install and read the comments page for mods before installing blindly. Seemingly simple, stable mods can cause all sorts of conflicts. Bring Out Your Dead edits the records of many, many NPCs in the game, which means that any other mod that edits that NPC is either going to overwrite Bring Out Your Dead's changes, or BOYD will overwrite the first mod's changes. (For most records, only one mod can edit them at a time. Only one. They don't "merge" records on their own, they just overwrite them.) Particularly problematic in Requiem, because even mods that just edit an NPC's appearance end up removing all of their custom perks, equipment, changed attributes and level.
The Skyrim engine also can't handle many scripts going on at the same time, no matter how good your machine might be. For example, I was using Burn Freeze Shock Effects for a little while, because it really made combat more immersive for me. Corpses would have burn marks, etc... but the scripts proved too much for Skyrim in large areas. I spawned a few dragons in Solitude using the console, turned on god mode (so that I wouldn't die), and watched them run around wreaking havoc. It didn't take long for the game to go pear-shaped, and walls and the ground itself started disappearing. I removed Burn Freeze Shock Effects and tried the same test again (on a new character, because you can't safely uninstall mods with scripts) and everything worked fine.
I highly recommend making good use of
TES5EDIT to resolve conflicts and
LOOT to sort out your load order. Mods with scripts are fine, but don't run many of them together. (eg, Requiem, Hunterborn, Wet and Cold, Frostfall...) I run a Requiem Skyrim installation and remove every
meaningful conflict myself using TES5EDIT.
If it sounds like I'm being paranoid, it's because I've had characters with 100+ hours on them with broken questlines and frequent crashes because I hadn't been careful and just installed whatever I felt like. It also kind of sucked, running into bugs that had already been patched by the Unofficial Skyrim Patches because a dozen mods in my load order overwrote those changes and restored the vanilla bugs.