Eat out less (the value for money is extremely poor in the UK)

Contribute more to an index fund.

Save harder for a deposit. High rent/shared housing is horrible.

Don't try to keep up with the Joneses. There'll always be someone richer, with a nicer car – you can't win that game. You weren't born in to money, don't even attempt to act like it. Live below your means.

You need to treat yourself far less often than marketing companies would have you believe.