Mods used in Clare's perfect playthrough are linked below under each title. I highly recommend every single one of these mods. Some of them are large downloads and long installs, but I wholeheartedly believe them to be worth it.

I do stand by your first run being entirely vanilla, please do that before entering the world of mods.

You will need ME3Tweaks Mod Manager to install all of these. If you want different hairstyles for ME1 and 2 I also recommend Trilogy Save Editor (if you mess up somewhere along the lines you can tweak it there too.)

I have included some absolutely game changing mods at the end (they're pretty much all for Mass Effect 3 but I will include them in a different section.

Mass Effect 1 

• A Lot Of Textures (ALOT)
  Incredible texture overhaul for all three games. Also download Improved Static Lighting (ISL) to install.

• A Lot Of Videos (ALOV)
  This is huge, but worth it. A huge video overhaul made by the community.

• LE1 Community Patch
  Community made bugfix mod for ME1

• LE1 Diversification Project
  Adds more people, moves some things around (you will have to look for Conrad Verner)

• Halcyon Hairpack
  A requirement for the diversification project.

• Advanced Weapon Models for ME1
  A requirement for the diversification project.

• Safely Skip the Conversation for LE1
  Does what you think it does.

• Galaxy Map Trackers
  Points out a lot of the places that you have to visit.

• Casual Hubs for LE1
  Puts the crew in casual outfits while on the Normandy or when visting areas with no danger.

• Saren Stages
  Visual changes to Saren as he adds more modifications to himself.

• Even More Hairstyles
  Clare's favourite hairstyle is in this mod pack.

Mass Effect 2

• A Lot Of Textures (ALOT)
  Incredible texture overhaul for all three games. Also download Improved Static Lighting (ISL) to install.

• A Lot Of Videos (ALOV)
  This is huge, but worth it. A huge video overhaul made by the community.

• Unofficial LE2 Patch
  A bugfix mod made by the community.

• Immersive Citizens LE2
  This adds a lot of people to areas like Omega and Illium, but it's brilliant.

• LE2 Prologue Framework
  Small tweaks to the opening mission.

• Safely Skip the Conversation for LE2
  Does what you think it does.

• Even More Hairstyles
  Clare's favourite hairstyle is in this mod pack.

• Expanded Shepard Armoury
  I think this might be required for another mod on this list?

• Casual Hubs for LE2
  Puts the crew in casual outfits while on the Normandy or when visiting areas with no danger.

• Tank Top Casuals for LE2
  I like Shepard in a tank.

Mass Effect 3

• A Lot Of Textures (ALOT)
  Incredible texture overhaul for all three games. Also download Improved Static Lighting (ISL) to install.

• A Lot Of Videos (ALOV)
  This is huge, but worth it. A huge video overhaul made by the community.

• LE3 Community Patch
  A big bugfix/correction mod made by the community.

• LE3 Diversification Project
  Adds more people everywhere. It also changes the Jondum Bau misson so that it triggers later and has a whole new level. The level maybe needs a little bit of work, but it saves missing it!

• LE3 Opening Remaster
  Extends the opening cinematic.

• Safely Skip the Conversation for LE3
  Does what you think it does.

• Even More Hairs
  A continuation of the hairstyles mod for ME1 and 2

• Appearance Modification Menu
  Allows you to change the hair without opening up the trilogy save editor.

• Expanded Galaxy Mod
  This comes with a huge caveat; EGM can totally change your game by a lot, however just installing the Core Quality of Life Features adds things like Casual Hubs, a chance to change your armour at mission launch, and set some timings of DLC missions. These are adjustable from a menu when you first install the mod.

• Immersive Emails
  This adds all the messages from the Bioware companion app for ME3 and inserts them into your game. All I can say about it is that at some point Garrus tells me I'm beautiful and that is worth the entire app.

• Character Consistency Project
  ME3 changes the look of some of the characters you meet throughout the series and this mod changes them back so they are recognisable at first sight.

• Dreams Remade
  The first dream my Shepard had when I installed this mod made me cry. It's such a welcome change to the overall dynamic of the game.

• Immersive Thessia
  Tweaks to the Thessia mission.

• Take Earth Back
  Overhauls the final section of the game to actually reflect all of the different races you have bought together for the final battle. It makes everything seem that little bit more worth it.

• IFF Dialogue Tweak
  Makes one plot relevant interaction happen between EDI and Adams. 

• Super Extra Party Time
  Can't decide between a quiet or rowdy party at the citadel? With this mod you don't have to!

• Tank Top Casuals for LE3
  I like Shepard in a tank.

Oh you're here for the batshit mental mods are you? Well they're coming soon.