QSK is spot-on. All that advice is good.
I fly IFR, privately, almost every week, but stick to the CIR currency to the maximum possible extent and keep all the endorsements current by practice.
I think the CIR process will make you a better pilot, IFR or VFR. If nothing else, you will be confident that those you are dealing with (ATC and other pilots) met the same standard. When the chips are down, that's worth a lot. There are certain disciplines learnt from flying approaches and maintaining altitudes that will help in all manner of flying situations.
There is a great danger in any type of private IFR (be it under CIR or PIFR) that the lack of organisational and systemic checks and balances allows completely insane situations to develop. An airline pilot has a ground organisation to provide support for diversions, equipment failures or just to discuss the situation with the other pilot. As a private IFR pilot (unless you are VERY lucky) you have no such cover. That means you must be diligent in decision-making and very honest about your own standards and those of your aeroplane. The 'personal standards' concept has a lot of merit for private IFR.
For me (and I do not suggest that it should restrict others) I have long applied the alternate minima as the go/no-go criteria for single-pilot flights in a single-engined aeroplane. OK, there have been some days when I cancelled and could have gone, but, well...
Can I suggest two major factors which you absolutely must consider?
First, your single engined aeroplane (unless it's the fantastic new G36 Bonanza) probably has only one alternator. An instrument approach on battery power is no fun. Unless you are very sharp and very confident about your alternator (just how confident can you be about such a device?) then there must be VFR conditions within available fuel range at all times if you are to stay safe. Even that criteria will depend on your ability to fly enroute some distance without radio, lights, pitot heat, transponder, navaids and (probably) the TC. Or worse.
Second, much of the weather when it happens in Australia is convective. This is different to Europe and America. You may read in the US Flying magazine of Cessnas/Pipers/Cirruses flying to 300 foot 1/2 mile minima and wonder why we never seem to do that here (well, north of Melbourne!)... Often enough they are doing it through stratus in smooth conditions with tops of 2,000 feet. Here, in the minority of the time when there is any weather about, it's easy enough to enter the cloud at 9,000+ and see nothing above 1,000. That means, even if ATC will let you drift happily down at 500fpm, perhaps 15 minutes of bouncy CU showers or worse, a STAR and maybe an approach to fly. Our lack of ATC means that many approaches start with a sector entry and holding pattern. It's no place to be unless you are sure you're on top of it. It is one thing to fly two ILS approaches a week in smooth stratus from vectors to final, but a completely different thing to fly one complete NPA every two months in cumuliform clouds.
I am certainly NOT saying not to do the CIR or PIFR for private flying, because if you do it should make your private flying an order of magnitude more effective. I strongly recommend however to make sure you get plenty of 'actuals' practice and be prepared to set appropriate personal standards.
IMHO, do the CIR, even only for NDB,GPS Arrival & GNSS NPA. You can then apply for a PIFR on the basis of that rating and get some extra latitude in the timing of your renewals.
I do hope this is some help.