Co-sign the whole antiperspirant thing too, which I mean you presume and not deodorant. I stopped wearing it due to crazy irritation and swelling I used to get. Not worn it for 10+ years.
Day to day, if I am going out I use Biosen (look for it on Google) as it is very gentle with no parades, aluminium, etc.
Also obviously good hygiene, ensure you’re scrubbing your armpits to remove old sweat and as someone has suggested, shave your pits.