24 y/o - earning 150k p.a

I work away in mining on an even time roster, on good pay for my age but can’t seem to make my money work for me.

My fixed expenses are roughly 3600 a month.
That’s including, rent, food, car loan,bills,mobile phone, gym etc

I have roughly $5000 left over for the month.
I normally give myself $500 a break for dinners with my partner, emergencies or just general leisure money.

So i’m left with give or take $4000.

Do I just save that $4,000 or invest?, my parents were never around to teach me this stuff and the internet changes what is right and wrong, smart or dumb.

Thankyou for your time