If you have a credit card you can contact your credit card issuer and request a credit limit increase. If you want your credit limit to be increased, you should show responsible credit card use. There should not be any delays, late or skipped payments during at least six months.
Another way is to consider applying for a credit card. Look for a credit card with 0% interest introductory period on purchases, like the Discover it® Cash Back. The card has a 14-month introductory period on purchases and balance transfers (when the introductory interest rate is over, the ongoing APR will apply) plus there is a cash back program. There is no annual fee and if you overlimit the card, you won’t be charged any fee.