Personally, my top tip for IR is "be kind to yourself". It's a very hard course anyway and it's hard bloody work when you're in the early stages....so be kind to yourself. Also remember to keep going - if you make a mistake in 170 or IRT then curse for no more than 5 seconds and put it behind you...if you let yourself "think" you've failed it, then you'll make more mistakes and probably will.
Also, I'd say you're likely to have more than one point when you think "I just don't get this". On those days think back to when you'd never flown a complex, or a twin and how hard THAT seemed back then....perspective that you WILL get it right helps a lot. Other than that - make absolutely damn certain you're in trim!