For many skills, G2/3 apply the skills the same way g1 did.
Thus from 0-10 1 point = 1 point
from 11-20 2 points = 1 point
from 21-30 3 points = 1 point
for these skills, you have to increase from 10 to 12 to get an effective skill of 11, from 12 to 14 to get eff skill of 12 etcandsoon