Edit: BEST leveling techniques for (specifically) certain skills..
Illusion: best place is Riften orphanage, as your illusion spells under master level can only effect up to 5 targets at a time, spam courage/wait an hour/respam until high enough level to buy rally, then use it, fastest way to accomplish leveling illusion. (especially since the ritual stone trick doesn't work until you have 90 skill level bc they can't effect undead.)
Alchemy:you only need to have at minimum gear that increases alchemy by 15%, the 25% isn't necessary, it will just take 2-3 more fortify resto potions used to achieve the desired %. Make sure you have a falmer helm and a circlet bc they can both be equipped at the same time, giving an added bonus to start. Farm your mats from Riften fishery barrels (salt piles/Cyrodillic spade tail/abacean longfin) and start from the river under the bridge at ivarstead and work your way west, that stream has the highest concentration of spade tail and longfin in the game, took alot of hours to figure that out. Then make fortify resto potion, use it, unequip an re equip your alchemy gear, make another, repeat until you face the thousandth+ percentile in your created potions, then do what you will to make other potions after that. (personally I like fortify destruction potions suped up, nothing like a 100k dmg firestorm
)
Alteration: telekinesis in one hand, detect life n the other, pick something up w tele and hold down detect life at the top of the first set of stairs in white run, you can see everyone in the city during daytime, I leveled it 15-100 in about 6 minutes...detect life you get as quest reward from trevas watch...telekinesis is bought from tolfdir at the college after leveling the skill to 50.
Conjuration: sadly best way is still to soul trap a dead body, it DOES gain xp based on the size of the soul, so a human tends to work best. Kill a bandit, an hour later, 100 skill lol
Destruction/restoration/sneak/one handed/2handed/archery: yes, all of these can be leveled the same method and ranging from pretty easily to very easily...you need the ritual stone, a fire rune/fireball spell, drop the rune and use fireball to activate it, double the AOE dmg (most dmg overall for cast time and cost) turn undead/repel undead/bane of the undead, those spells grant the best xp of any resto spell you cast...your sneak skill will level fastest from sneak attack damage because you can gain up to 12x the amount of sneak attack damage you deal as xp, that damage ALSO applies to the weapon your using for skill xp...you can Rez a bunch of bandits, sneak behind them and get the attacks off and you will level those skills as fast as you can...
Pickpocket: Sibbi black briar in Riften jail, get caught, break out, kill the guards(<--a must or it won't work) then have about 1k gold, start by placin 200 on him through the bars, then take it back, level everytime until 40-50, then up the amount to 400g and continue, around 70-80 up it to 800 then 90-100 is the 1k. Of course w the bonus pickpocket enchants and potions you can do this much more effectively lol
Speech: can't be exploited anymore at the meadery, best thing is to make those super expensive potions and go sell them 1 at a time to the shops to clean them out, it bases the xp off of the value of the item sold when you obtain the money even if you oversell. So that makes for pretty fast leveling of the speech skill, just a little more time consuming than 30 minutes at the black briar meadery lol