On the ILS, pay particular attention to the section of the approach plate where it gives you a rate of descent to go with your groundspeed.
It's easy to fall into the trap of chasing the glideslope needle with lots of pitch and collective inputs, distracting you and causing you to get off track on the localizer.
Instead, focus on establishing the given speed (90 knots or less -you're a helicopter!) and rate of descent as best as you can; the resulting glideslope will be stable and you'll be able to maintain it with a minimum of pitch and power inputs. Keep cross-checking your speed and rate of descent in conjunction with your glideslope needle.
Having taken care of the hard part -the glideslope, you will now have the time and the brain power available to take care of the easy part -following the localizer.