My biggest hurdles for the IA was learning the "scan" and IFR communications. Here are some suggestions for stuff to do between flights:

Get X-Plane and a simple joy stick. I don't know where you are in your training, but being able to "fly" at home will hone (or build) your instrument scan and you can practice the approaches/holds you'll be doing in real life. You don't need the throttle quadrant, rudders, and yoke as this exercise is for the scan, plus they don't model the actual a/c very well.

If you're close to an airport, an aviation scanner will help with learning the lingo. Or listen to ATC on the interweb.

I now use x-plane to keep my scan skills current and to "see" what's it going to be like going into a new airport.

Have fun!