I agree that flight sim can help you a bit. Pick a Beech Baron (or any other aircraft that is close to what you fly in) and do some manual flying, interceptions, holdings, hand flown ILSs etc...
While I agree it does not really come close to the real thing it helps you with certain things like
instrument scan
which holding entries to fly
reading charts & flying at the same time
thinking about MDAs, memory items etc...
Not bad imho, I keep doing one or two approaches every two or three days to stay fit.