Improving your credit takes time and sticking to basic principles.  Basically, you're improving your credit history over time, which then will have a positive effect on your credit score.  You can begin to improve your credit history by taking a close look at your credit reports and use the following tips to chart a plan of action for improvement. 

Since payment history is the most heavily weighed in determining your credit score, the best thing you can do is to make on time payments and slowly build your score from there.Lower your spending to credit line ratio; anything round 30% is safe.  For example, if you have an $8,000 combined credit line, try to keep your monthly balance under $2,400.  Remember, your credit cards are for credit building purposes, not an extra source of income.  It is also important to pay as much off as you can each month.Pay down any credit cards that are near their limit.  Your credit score suffers if it looks like you have maxed out your credit card.Frequent inquiries from credit providers can decrease your score.  Do not apply for too many credit cards.Keep cards with a long healthy history.  Creditors want to know that you can be consistent and manage your credit responsibly.

Removing Unfavorable Items on Credit Report

According to Experian, one of the nationally recognized credit bureaus, the timing varies for different types of negative elements, such as a delinquency or collection account, to be removed from your credit report.   These elements have an impact on your overall credit history until they reach a certain age.  Basic inquiries, other than your one free credit pull each year, will say on your record for two years.  Late payments (delinquencies) are there for seven years.  Public record items, such as a bankruptcy or medical claims, remain for seven years, but there are some bankruptcies that could remain for 10 years.  An unpaid tax lien will be there for 15 years.  Therefore, it's very important to be diligent in keeping your credit in good standing.  It will affect you for many years to come.