I just signed up to donate tomorrow. It'll be my first donation in like 2 years, after being diagnosed with low iron. I did get give the ok from my doctor to go back to donating much longer ago, but I was a little suspicious about the circumstances,* so I decided to put it on hold longer-term.

If you don't already know your blood type, go ahead and sign up anyway. There's no lack of use even for other blood types...and O-type is the most common in Australia anyway. Donating whole blood is super easy. The worst part IMO is actually the tiny pinprick they take before the donation to determine your haemoglobin level. The needle used for the actual donation is a complete doddle. You may get a little light-headed afterwards and it's probably not a good idea to do heavy exercise, but that's a very short-term effect.

As a bonus, they tell you your ferritin level every 10 donations (including first) and haemoglobin every time. And they'll tell you what your blood type is.

Oh, and you get free snacks afterwards.

* My ferritin levels were only just inside the normal range, after a few weeks taking supplements bringing it up from levels that had my sister (who is a doctor, though not my doctor obviously) saying "YOU ARE SO UNWELL HOW" and "Your bloods are like an 80 year old lady's". And I was told to stop taking the supplements at that point, despite not much being done to fundamentally change anything.

It would be good for them to update their eligibility quiz to include medications. I passed the quiz (and am type O-), but can't donate due to medications.

For anyone curious: https://www.lifeblood.com.au/faq/eligibility/medication-and-medical-devices/prescribed-medication