Sometimes I'm still a noob

I've seen loads of times over the period of time I've played L2 comments about players plussing their skills.

How? When? Why? (ok ignore the why :p)

I genuinely know nothing about this and I'm interested to know more

76+

Ok that's the when, now I just need the how :D

don't worry about it, you'll never get to that point... (78)

well, if you REALLY must know, you waste xp/sp to over-enchant a skill at a trainer. it can blow up on you and go back to +0 too.

Thanks for the info - although I'm not sure about the 'never get to that point' comment :)

certain skills may be overenchanted at lvl 76
to enchant a skill you need xp sp and a secret book of giants (made from castles or olympiad)
1 + on a skill at 76 is equal to about 2.5% and the equivilent sp
if a skill fails it gets reset to +0
each lvl after 76 increases the success rate of enchanting skills, eg a +1 mechanic golem at 76 has a 80% success rate at 78 it would be more like 98% (why most ppl save enchanting for lvl 78)
some skills have branches where you can choose how to enchant the skill (can only choose 1 type) an example might be blunt mastery which can be enchanted for pattack or crit rate, after a certain point both paths add run speed as well

Go here:

http://l2p.bravehost.com/skillenchant.html

Thank you all for the information, fully explained, I understand now :)