I'm playing as a level 18 mage (High Elf, The Lady) and was just wondering if there was a "limit" to the skills and attributes about when it starts to be a waste to invest further points into it.

I know, the skills will raise by using them anyways, but how about the attributes? For instance, I have 99 in intelligence now, 91 in Willpower, should I start neglecting those now and invest into other attributes? Or can I never have enough?

Skills and attributes max out at 100, through the normal mechanics of gameplay. If you raise your SKILLS past 100, via spells or enchantments, you get no added benefit. Attributes continue to give benefits when they are artificially raised past 100. Otherwise it depends on what your trying to do. Like, if you have any +5 bonuses in other attributes, when you level up next, I would use those now and cap off the ones that are 99 later.

Since you are a mage (and not of the Atronach birthsign), it is worth your while to get both your intelligence and willpower to 100.

Okay, thanks. Never knew attributes stopped at 100, too. What does artificially raising skills mean? With spells, enchanted armor and /or training? Or does this refer to mods? (PS3 version, here.)

Edit: Oh, must've overread the part were you said what it means.^^

That would be with spells or enhants. Attribs can be temp raised by potions as well. Training is perm. It's the same as you raising the skill manually.

EDIT : Acad is right. About the Intel and Will. Although I would way the difference in using 1 point to get an Attrb to 100 from 99, If I had another like Strength or Endurance, with a +5 bonus. But if you're playing a pure mage, chances are that you are not using the skills to gain bonuses in those Attrbs anyway.