Hi, my hunter is now over 260 skinning lvl.
My advice is, keep hunting monsters/animals which U can skin it after U killed it.
If your character is lvl 15, U should be able to kill mobs at lvl 13 to 17 or maybe up to 19.
The higher the lvl of the mobs U killed, the often or earier gain on skinning lvl.
My hunter is lvl 36, I killed lvl 38 turtle and the skining lvl on the corpse is still green to me(which mean seldom be able to get a gain on skinning, if is in yellow colour then mean can get a decent gain, if it is orange colour then I will be able to get a gain on each skinning)
But the important thing is, just keep hunting those skinable beast of about same lvl to your character.
There was once that someone killed a lvl 40 beast and I was able to skin it and get a gain. :)