Sometimes, when I felt that I had Accomplished a good amount, I like to take the time to sit back and hone my skills as a Warrior-Mage.
So I say, "What better way than to fight something that can always come back for more?"

So put on my Robe and Wizards Hat and Conjure my good friend the Flame Atronach.
I strike it a few times with a Two-Handed Sword (My Skill with them was really Low) and I gained some skill levels.

Conjuring Familiars and Atronachs for training partners is fine if your combat skills are weak and you an enemy that won't attack you for a few hits.

I do, however advise against using this training method if you are and archer type class for training takes a sizable period of time and number of Arrows because their corpses WILL disappear and will NOT recover any arrows.

The Following skills can not be raised in doing this training.

Alchemy
Lockpicking
Pickpocketing
Smithing
Sneak
Speech

This next list of Skills can be enhanced using this method, but are quite specific.

Archery: Can be raised, but consumes arrows in the process.
Enchanting: Buy using Soul on you Summon you can seal its soul in a Soul Gem, but this requires the appropriate conditions. And is better used on Adept of Expert Summons.
Soul Trap - Conjuration Spell
Soul Gem equal to the Summons Soul Strength.

All other skills can raised well by using this grinding tactic. I hope this helps any players, who find their current power to a little lacking.

This is a valid tactic, but don't you find it extremely boring? Wouldn't it be better to just play the game and level up naturally?

who cares? yes, its easy to exploit things to level skills up quickly. this news is about 10 years old in the TES series.