By far the best piece of advice for anyone who wants to be financially sound. Wait to buy that car.. even though your friend just bought one. Save your money and buy a Mercedes later along with a nice house... all the while your friend, who is driving a now five year old, mediocre car, is unable to afford anything else.
I think this saved our marriage (kidding) but there are no fights about money, that's for sure. He has his to spend on race cars and I have mine (and the adult clothing fund) to spend on my clothes. Hey, don't judge I just outsmarted him! Lol