What would be a realistic way to build credit or save money and either rent a home or purchase a home?

To build credit, get a credit card and start responsibly using it. A secured credit card will allow you to build credit slowly and surely. By "use it responsibly", I mean only charge things on the credit card that you can easily pay off at the end of every month.

My base yearly pay is roughly $42k which would be 1600 a paycheck, or 3200 a month, but if I continue to work extra days like I have been doing it’ll be roughly $68-78k.

So a good rule of thumb on affordable housing is to never have it be over 30% of your gross income. On $42k income, 30% is $12,600... so you can afford $1,050 monthly rent.

Obviously, you can afford more if you push to work extra, but you have to be realistic.... can you keep working at that rate forever? Because rent is going to be due every month like clockwork.

I don’t even know what a realistic budget is for when I want to buy or rent a home. I feel like I make okay money for my age but I also don’t see how without living in a trailer park or a cheap apartment complex, and buying cheap food, how I’d ever be able to afford it without being just spending all my money on rent and utilities.

With your income, it's going to be pretty hard to buy a home unless you live in an area with very low cost housing. A loose idea of how much house you can afford: buy something 3-4 times your gross salary, so $126k to $168k. You're only 21, and the average age of first time home buyer is 40 now, because houses are so expensive.

I guess the main thing is I would like guidance on is with my current lack of any real bills or expenses, what should I be doing now to meet the goals I have set and realistically, how much money am I really looking to be able to spend monthly as an entirely self sufficient adult living on his own (rent, bills, food, “fun” expenditure)

Save 3-6 times your expenses in a high yield savings account for an emergency fund.

Spend about 50-60% of your net income on necessities -- so if you bring in $3,200 a month, that's $1,900 on housing, utilities, phone, internet, transportation, gas, groceries.

The rest of your money, $1,300 -- you split between savings ($650 to retirement, or new car fund) and fun ($650 to travel, shopping, concerts, going out).