Yes you can gain on failures. I find, however, that my very best skill gains occur when I have 45-55% chance of success and a lot of targets (I don't want to spend all my time searching rather than training!)
Use a range of instruments: regular, exceptional and slayer to stay within that range on the same creature. You should probably be provoking Ogre Lords with regular instrument or Kits with an exceptional.
I usually train with a homemade chart that I use to record the creature, # of attempts and skill. Helps me to see how many attempts I make to gain 0.1.