Trying to get a small loan?

i only make 9000 a year..i have 2500 in credit card..but i been paying the min. payment the last year 1/2..my sister has low income such as me..i dont think she really has good credit..she been paying her car and was late 1-2 times..if we apply for a loan together jointly..will this increase our chances of getting the min. 7500 dollar loan..my sister was approved by a dealership cuz she had money in the bank statement showing she has money**.now we trying to get a 7500 loan