For scripts you go to the chemist you got the scripts filled out at and ask for a tax statement. Hopefully you have a regular chemist, otherwise you will need to go to each chemist. They usually ask you to fill a stat dec out to get the statement.
For Medicare you can get the statement online if you are registered online and and also get one from your PHI as well. Ask for end of financial year itemised statement for tax.
You get 20c in the dollar for medical expenses after you hit $1500 threshold.
For anything that you didn't claim from either PHI or Medicare, bundle the receipts and add them up or give them to your Tax agent.