The credit limit is the maximum amount of money you may charge on your credit card. This limit is mainly determined by your credit risk. So, it depends on the terms of your card, on your income and may be changed according to your credit history.
About How to Boost Your FICO Score
Good Credit Scores takes patience and persistence and there are quite a few ways to legitimately give your score a boost when needed. Over the long haul, you'll be rewarded with a solid FICO Score.