Learn to fly your plane by the numbers. To do that, you have to go up and fly and take notes. Key flight regimes can be boiled down to an attitude (level, one dot nose high, one dot nose down, etc.) and a power setting that yield predictable performance at a desired airspeed. Key flight regimes are level approach speed (e.g. 90 kt in level flght), departure climb at Vy, 500 fpm descent (say at 90 kt, a common approach speed). Commit these to memory or print them on a post-it on the panel. This way, you can quickly put your plane in the proper attitude and airspeed for a particular approach or departure flight maneuver.
For example, in my AA5, AI level and 2100 rpm will yield 90 kt level flight. Pull the throttle back to 1900 rpm and you get a 500 fpm descent at 90 kt, close to perfect for an ILS or LPV approach. Pull back to 1800 rpm and you get a faster 700 fpm descent for "dive and drive" descents, etc. A departure climb is full throttle and 2 dots up which is about Vy (78 kt) and 500+ fpm, depending on load. This is the old "power plus pitch" = performance gig, and every instrument pilot should know the basic numbers for the plane(s) they fly. It makes maneuvering much simpler to accomplish.