If you are in twenties or early thirties and remain single, earn $3,000 after tax per month, you will probably save $1,000 if you, let's say, spend $500 to $800 on rental, a guest bedroom in a shared house/apartment, $500 on food, $50 on utilities, $150 on phone/internet bills, $400 on commuting costs or gas/maintainance if you have a used car, $200 on occasional entertainment or others. This $1,000 savings will allow you to invest or place a house down payment when time is ripe. Is this possible based on where you live ?
It's easier said than done, and I'm surprised you didn't include a health bill or insurance. A job that pays $3,000 per month is not a joke, it will require your strength, mind, brain, and focus, and as a result, you will be stressed out at the end of the day, and stress upon stress weakens the body, probably causing breakdown and endangering your health, I believe good health is a good wealth, and it should be included.
Now, your estimates depend on where you live. I can survive on $500 in food, but if I buy everything I need for cooking, I will save even more. However, you cannot expect someone living in a well developed country in a city to survive on $500 per month, I doubt if it will last a month.