Regarding the leans, if I get them any more than a tiny bit, this technique was shown to me by a very experienced old pilot - I'll make sure I'm wings level, or in a rate one turn if required, then close my eyes for around a second and picture the aircraft perfectly stable in the correct attitude. Then I'll confirm what I just told my brain by continuing the scan. So in a wings-level scenario I'll picture the aircraft nice and stable in S&L flight, then scan AH/TC/DG to confirm there's nil bank angle, nil rate-of-turn, and nil heading change. And if there's a suspect instrument, eliminating it from the scan, and potentially covering it if the error is bad.
I also find keeping a nice light touch on the controls when in IMC and consciously not over-flying the aircraft (make a point of relaxing and being as "casual" as possible, get yourself in the state of mind that you're a professional and you've done this a lot) helps a lot. I find the more relaxed (less nervy) I am in IMC, the less I overcontrol the aircraft, I'm less susceptible to the leans, and the more accurately I fly the correct track and profile.