There has been plenty of advice on stocks and shares and ISA already.
Be willing to relocate, I relocated to a major city knowing no one, I then met DH and we relocated again.
Never ever lend money to anyone and never ever let anyone know how much money you have.
Say no to stuff you don’t want to do, I see so much fretting on MN with people committing to stuff they don’t want to do with people they don’t even like and spending £££.
Ask for discounts and barter, I have received many discounts over the years.
Buy decent quality and only replace what needs to be replaced, consider why you are thinking of trying a new product.
Work out your entire yearly expenses, easy if you never use cash. I know what I have spent to the penny for years except lockdown year. Then make adjustments if needed.
Decide on an end goal for all this money. Mine was to retire early by 55 so I could do the voluntary work I wanted to do and then when DH joins in 2 years we will be travelling for a few years.
I was given 1k when I was 18, I invested mine and my sister spent hers immediately, understand delayed gratification as a concept.
Then the hardest part, if you want to partner up, take your time finding someone. Anyone lazy, bad with money, or too complex a life, just don’t go there, it doesn’t matter how pretty he is or amazing in bed.