Get the biggest chart you can find and cover all the instruments but fold a corner so the FI can see the alt, it doesn't need to be in date BTW. Then fly and be happy.
Every time you change the throttle adjust your nuts. If its power up use your left hand power down use your right. It won't make a difference but the fact you are thinking power up and power down will stimulate your brain and it will happen.
The instrument thing is only really solved completely by becoming a instructor and flying from the RHS seat all the time. The night rating restriction removal gives you a black belt in flying by attitude and engine noise.
Don't beat yourself up though its a very common problem even with people with no FS time. Every instructor has there own method of dealing with it. Be it post-it notes or a GBFO chart across the lot depending on there own limitations. Best solution I have seen is 2 carboard cutouts for the alt and the air speed with +- 100ft and +- 5 knots everything else was covered from hour zero.
Persoanlly if i even suspected instrument fixation the whole lot got covered. And the basics were revisited until the student was able to trim for all modes of flight without the things. What does get to annoy though is students without anything can fly a perfect circuit at cock on circuit height, correct airspeed etc without any instruments at all. Then proceed to make a complete bollocks of it when they can see only the alt, rpm and ASI.
"look out the bloody window" must be one of the most used phrases in aviation training.