Request sticky if you would so like to. I'll update this thread when new and better ways to upgrade skills occur. I will give credits in a bit.
You can take back the gold you get from skill trainers by making them your companion, and by pickpocketing it back from them after you get training. For your magic skills, get 100 enchanting, all 5 enchanter perks, insightful enchanter, corpus enchanter, extra effect (extra effect not necessary, so i guess you only need like 70 enchanting). enchant a ring, necklace, body armor, and helm with -25% [insert magic school here] magicka cost
make damage magicka regen, damage stamina regen, invisibility, paralysis, and slow potions these are worth the most and thus give the most experience
Slow: deathbell, large antlers, river betty, salt pile
paralysis briar heart, canis root, imp stool, swamp fungal pod
my favorites are hanging moss and blue mountain flowers... very easy to acquire and very good exp/value
Cast oakflesh over and over while you are in combat with an enemy who is stuck in the water.
Block and Light and Heavy armor
Just go into a cave/mine with a really low level enemy and back into a corner. You can then just elastic-band your block button down. I'm currently doing it, seems to be a slow skill to level just like in Oblivion. Make sure you set the difficulty down so you don't die.
1.Buy the bound sword 2. Find slaughterfish 3.Stand at the edge of water so slaughterfish can't attack you, and so that you'll still be in combat 4. Cast bound sword (don't dual sword it), sheath your weapon and repeat.
You can get the Apprentice Conjuration magic perk to make this process go by faster. This process is so quick you can have 100 conjuration in little over 1 and a half hour.
smithing & enchantment & speech
1. buy/ mine iron ore/bars. 2. acquire leather strips. 3. smith as many iron daggers as possible 4. enchant iron daggers with weak enchantments. 5 sell daggers 1 at a time for good profit.
Or if you want to train Speech very quickly.
1. go to riften, black brian meadery 2. talk to the guy at the counter, ask him to tell you about the meadery 3. use the persuade option. if it fails, bribe him gold instead, you need atleast 26 speech for persuasion to work i think so if youre not 26 yet, youll only need to bribe a few times to reach lvl 26 4. repeat 5. 30 minutes later, youre level 100
Go to the Greybeards (after you are revealed to be Dovakiin) and sneak attack them. They won't fight back.
Dual Cast courage on any NPC
All combat skills (Destruction, One Handed/Two Handed)
Put the difficulty all the way up, cast a Frost Atronach spell and wail on it. Or, do the Dark Brotherhood quest to acquire Shadowmere and put the difficulty all the way up and wail it. Once it it enters combat, heal it when it reaches low health then wail on it some more.
Get a buttload of lockpicks and find a master lock (check out the Dwemer Museum for some high level locks) and continue to break all your locks.
Assuming youve already gotten a high enchanting level, enchant at least a ring and necklace with fortify pickpocket
1. go to any town 2. pickpocket 3. repeat
the success rate is crazy high with 1 or 2 measly fortify pickpocketing enchantments valuable items/things that weigh a lot give the most experience if you get caught just take the 25 gold fine, dont bother saving/reloading etc once youve stolen most of the valuable things in one town, move onto another more valuable items show up when you have a higher pickpocket
Get a high level ward spell, find a necromancer camp and continue to deflect their spells.
A good one for restoration also when you are following the mages college quest line you will acquire a spell called Equilibrium (Alt school) it converts health into Magika I put Quick heal in one hand and Equilibrium in the other just kept them running and advanced my resto tree to 60 in about 15-20min.