<prompt> Human: Each month, I earn more than I spend, and I have no debts. I have 2 credit cards; I try not to use more than 30 of my credit limit for each, and I always pay the balance automatically on time and never incur any fees. My credit score is in the low 700s and I would like to improve it. I recently switched jobs and my salary has doubled. So I am thinking of applying for a third credit card with a much larger credit limit.My question is, if I always pay my balance each month, what percentage of my monthly expenditure should I be paying with credit cards in order to improve my credit score the fastest? 100? 50?To clarify, if my monthly expenditure is 3000 and I wanted to always stay below 30 credit use AND I wanted to pay 100 of my expenses using credit cards, I would need a total credit limit of 10k. Since I am currently approved for a total credit limit of around 2k on the other 2 cards, this would require me to apply for a new credit card with limit of 8k.Is it purely a question of what credit limit I can be approved with my credit score in the low 700s?  <response>: Have you asked your current cards for credit line increases? Some of them do them on the website you pay.Charging more to a credit card wont increase your score, basically you just want utilization below 30, so increasing your credit lines sounds like the best move.I personally charge everything I can to my credit cards to get 2 cash back I use to fly to visit family for the holidays. 