Next up on the ladder, some light IFR actual. Also just have to fly
more. Rust never sleeps.

The best thing you can do is fly x-country a bunch and file IFR
everywhere you go, regardless of weather. That will get you used to
all the stuff ATC can throw at you.

I agree with this. Flying IFR in mostly nice weather into busy
terminal areas is what I did for awhile. Good getting used to wacky
arrival procedures, altitude (20K feet), etc. I also did some weather
flights for decision making. Was over a year before I asked the wife
to sit through an actual ILS approach into an airport in IMC. I may be
more cautious than most.

Chris