Im surprised no one here has figured this out yet.
Your balance of your accounts are reported to credit agencies on a certain day each month. What your balance says on that day is what effects your credit score.
You can find out what day this is by doing an experiment. Spend some money on your card, say 250$ out of the 500$. Open an account with one of the credit score checker websites (ex: Freecreditscore.com). Log in and look at your credit score everyday for as long as it takes to notice when the 250$ balance was noted, plus an interest, and minus any payments. Then pay off your card, or pay off a certain amount. Log in everyday to see when that payment was reflected on your credit.
By doing that, you will be able to see when you want to have your balance down below or at the 1/3 balance HeyHey recommended.
You build credit by having credit cards, and by not spending a lot on those cards. Your score moves up and down based on your debt to available debt ratio. In other words. Banks and credit scores like when you spend on credit cards but do not spend all that is available to you.
The banks sees these things. Your balance. Your credit limit. And your highest balance spent. Im not exactly sure what they think about the highest balance spent, but I do know that your credit is greatly effected by what your available balance is.
If you max that card out to 500$ and your balance is at 500$ when it is reported then it will negatively effect your credit score. If its at a reasonable level then it will push your score up. Each month is an opportunity to make your credit score move up or down.
So with that experiment I laid out, you can actually manipulate your credit score. So get started.
btw, Im pretty sure that you dont even need to keep a balance once you have spent once on it. I think it reports good credit when you are at zero balance.
Also, you cant hold me to this. I haven't looked at it in a few years, but Im like 99.9% sure its still like this.
Im also a little unsure if the bank reports it or if the credit agencies pull it. Either way, I know it worked.
I would follow HeyHeys advice. Spend 1/3 then make payments. Next thing you know, you will get a credit line increase. Dont go and spend a bunch of money on it. Credit Cards can be used as tools to build credit, but they can also destroy your finances. Be careful and dont get sucked in.
Use it only as a tool.