* Very minor spoilers. *

If you DON'T want to (or for some reason can't) use a mod to delay the appearance of the expansion content then it's still fairly simple to avoid it: don't take the boat to Solstheim, and don't take the teleport to Mournhold. You will get attacked by an assassin sometime during your first few rests as a result of the Tribunal expansion, but as soon as you talk to a guard about the issue, the assassination attempts will stop and nothing more will happen until you visit Mournhold.

(Just don't use the assassin's armor, since it's Tribual-quality.)

OTOH, aside from that armor, most of the unbalanced things either require a fortune in cash (relative to a starting character) or fairly high skills/survivability to obtain, which won't be an issue early on. The few things you can do in Mournhold that won't get you killed at low level don't pay much, and aside from a couple of talk-to-people missions and a single escort (which likewise don't pay much), you'll get splattered in Solstheim long before you reach anything powerful.

I don't think the internet starts every morning until someone asks about Elder Scrolls mods.

Okay, but how do I do that? I'm assuming I have to find some file somewhere to do those changes, but I have no clue what to look for.

Just use type it into the console while the game is running and your save file is loaded. I'd advise against doing it, or at least against setting it to 100 (50 might be more reasonable) if you want to actually improve those skills (it's quite rewarding to reach level 100 in each legitimately, though it does take a long time. Also speed governs other skills as well, like in Oblivion, so setting it to 100 will result in a character who's overpowered in more ways than just movement speed). One other interesting quirk of the movement system is that if your acrobatics is higher than your athletics, jumping along actually moves you faster than running, though it drains your fatigue much faster.

By the way, I assume you are running, rather than walking?

Open the console (no, not the X-Box, but the console on the PC version of the game) by hitting the tilde button (under ESC), and type in the commands.

First time playing I would recommend trying without mods. Just play for a few hours, until you figure out what you want to change, add or remove.

But in any case, here are some of my personal favorites:

Morrowind Comes Alive
Adds tons of different NPCs and animals around the towns and villages.

Giants Ultimate & The Wilderness¨
Those are two mods that add a bunch of creatures and monsters to the wilderness

Magicaka Regeneration
Regenerates magicka without potions or having to rest, as long as you don't have the Atronach birth sign

Galsiah's Character development
Changes the leveling system, so that stats are set according to your skills. So there's no level up screen or anything. Tend to use the fairly easy setting for this one, because the default values lowers the rate of skill gain, which I don't have the patience for.

SilentCharGen
Makes all the various NPCs in the beginning shut up, so you can just run through it. But the beginning is worth playing through at least once.

Wizard's Island - Scourge of the Frost Bringer
An absolutely enormous mod with a mainquest and several sidequests. Almost like an unofficial expansion. There's new music, items, creatures and a couple of islands. Most of the mod's mainquest takes place on a large snowy island (this was released before Bloodmoon), and you can't return to Morrowind until you've finished the mod's mainquest. There's some questionable design, bugs and spelling error, but I still loved it the first time I played through it. Just make sure to get the final patch and the snow fix.

I for one do not recommend this mod, because it goes against TES lore at a lot of occasions, and a lot of creatures by it just ... Don't belong.

Spent a delirious amount of time on Morrowind and enjoyed every second of it like I seldom enjoyed any game, BUT i always play vanilla, so, I can't really give advice on mods.

One think i don't like with modders who "enhance" graphics, is their tendancy to "fix" things according to their tastes, that are sometimes even more nerdish than the developpers. In particular, while graphically ameliorated, all characters tend to be more "pretty" and females more "sexy", in mods, because for these players, "better looking" means "hotter". This irritates me. Same issue with the System Shock 2 enhancements : the cyborg midwives were way cooler when they didn't resemble some borg pin-up. Maybe the graphics were lower quality technically, but they were more clever (and unsetling) in terms of content.

So generally, I find the original authors' vision more interesting than the modding geeks', and slightly slightly subtly less fantasy cliché, and I prefer to pay the price of technically clumsy graphics for that. The only think I was hesitating to mod was the definitely beyod hideous "enchanted" effect (smelles too much of gazoline), but even that, I took it as a prohibitive drawback of having magic armour, and just kept non-magical things instead, which was still viable until the add-ons started to g a bit crazy about monsters strength. But then again, I didn't play the add-ons much (Tribunal was okay, Bloodmoon was disappointingly bland).

So there, opinion on mods in Morrowind and in general.

You do realize that all the Morrowind overhaul does is add higher resolution textures (and make Dunmer red eyes glow faintly, which is actually kind of cool - and makes the red color look ... Not completely ridiculous.) At any rate, all armors, models and ... Pretty much everything is the same. So no sexy armors and hot warrior princesses with big tits, it's still the same thing with prettier textures, that allows you to see further and adds some misc items which are actually true to TES lore and only exist so more detailed textures don't look weird.

Actually, if I remember well, all the weird (and technically a bit 'rough-on-the edge') faces were made handsome. I preferred relatively low-tech representations of bland, ugly, weird, faces, than crisp high-tech representations of some fantasy soap-opera-ish everyone-is-attractive universe.

No, they're just faces from morrowind with crisp textures - and faces in vanilla morrowind were from soap-opera-ish everyone-is-attractive universe, they were just low-resolution, therefore didn't actually resemble faces all that much :D At any rate, don't like crisp faces? Well turn off better faces in launcher, takes about 2 seconds, removes this 'issue'.

Figured I'd ask (not to derail the thread), but if I were to install the first two mods, would the install order be something like:

Game and expansions
Unofficial patches and fixes
Morrowind Overhaul
Tamriel Rebuilt

I've never really gotten into Morrowind before, so I don't have any knowledge on how modding it works.
I just know that sometimes you have to do things in order.

Game Of the year edition
Unofficial Patches and Fixes FIRST
Morrowind overhaul Looks SHIT!
I just take MGE out of it and Add my own packs
Tamriel Rebuilt NOOOOOOOOO DO NOT INSTALL IT IF THIS IS YOUR FIRST PLAYTHROUGH IT WRECKS THE GAME!!! that's what I did and thats why I never went back to it NO, NO, NO, NOOOOOO!!