Experiment with finger placement. You don't necessarily want to use the tips. In fact, I'd recommend against that unless it's especially comfortable for you. Use the pad, or even move up a joint and use the space between the first and second joint from the tip. Also, keep your fingers straight, but not rigid. It shouldn't feel like work. Try to stay relaxed, and keep a light touch; just enough to seal the hole. You'll need the speed later as you advance. If you treat it as would a water leak(heavy hand), you won't be able to do the faster material, which is 90% of Irish music.