<prompt> Human: Im 25, and I get paid an average amount for my line of work 75k, which is good for my project location - in the Midwest - but below average for New York where my actual office is. I dont expect to be sent to New York for at least year.Following the advice of the good people at rtravel, I have taken two credit cards to make hotel and flight bookings Id have to make for work anyway reimbursed. One is the Amex Starwoods Preferred Guest card, the other is the Amex Delta SkyMiles card. Both cards have 0 fee for the first year, then a 95 annual fee after. They give me extra points and miles per dollar spent at those hotelsairlines. The problem is, since my credit history is very new 2 months, Im not a US citizen, my credit limits are 1000 which I will easily max out in less than a week. My flight expenses a month come to about 3000, and hotels about 7500. The PF wiki tells me maxing out my cards are bad for my credit score. How can earn more reward pointsmileshotel nights or returns on these expenses? Should I apply for more cards?Also, what are my options as a non-citizen to invest for retirement in the US? My employer does not offer a 401k plan. Can I invest in Roth IRAs? Sorry if these questions sound stupid, or if any of this sounds like gloating - Im genuinely only looking for advice. I have about 2000 in savings, no car, no property or assets to speak of.Assistant: Once your credit is newer you may have to wait a few months to let it build up, I wouldnt apply for a bunch of new cards in a short amount of time. If the cards you have are with who you stay with and fly with, Id maybe wait a few months and see if they will increase your credit on them. In the mean time, you may be able to pay them off multiple times a month to stay under the limits.Human: Thank you.In the mean time, you may be able to pay them off multiple times a month to stay under the limits.Is that how it works? My understanding is that I can use credit cards to pay for a fixed amount every month 1000 in this case, no matter how often or how much I pay back the balance. I think my Discover card works like this Im not sure. If thats not the case, then I might be able to make it work with the current credit limits.Assistant: Yep, credit cards are a line of credit. You can change 999 on the 1st. Pay 999 on the 8th. Charge 999 again on the 9th, pay it off again on the 12th, charge it again on the 13th, etc etc. Any amount that is borrowed can be paid at any time some make you wait until the amount posts in a few days, but it works pretty much the same. Once the amount borrowed is paid, the full amount is available again. I get paid weekly, so when I take work trips I pay off my credit cards every week, leaving the full credit limit available again. Human: This is very good to know. Thank you!Assistant: It just wont let you pay it off if the charge is pending so you have to wait u til the charge posts. Human: I think this doesnt work for Discover, they seem to have a fixed limit per month.  <response>: I pay my discover offer multiple times a month. 