So, where to start first.  Do you know what your credit is like right now?  Do you know what your FICO score is?  It does change frequently, so what it was 6 months or a year ago is probably no longer correct.  Also, it is important to note that the credit reporting industry is changing how it grades and reports credit scores.  This is akin to a Google search algorithm update - where you ranked yesterday or last month has nothing to do with today.  This is why it is so important with your credit to routinely at least once per year pull your credit and find out where you stand and what is on there and what your score is.
 

Another reason to pull your credit at least once or even twice per year is that, per consumer watch guard agencies and as revealed in conressional hearings earlier this year and last year - many - as much as 60% or more of credit reports have errors which will cost the consumer in the way of higher rates, being turned down for loans, and even a loss of a job (many employers now review potential employee credit reports and scores in their job decisions).   There is also one more reason to routinely pull and check ones credit - fraud!  Not fraud by you.  What I mean is credit card fraud and similar where someone else opens up credit cards and loans in your name and then absconds with the money and you don't find out about it until the collection agencies start calling for stuff you do not owe and never bought.

Credit card fraud and similar financial fraud is on the rise and you have to be vigilant for it because it can completely mess up your credit and take years to fix.  So the most important part of fixing your credit is to first pull your credit and take a good look at it.  There are 3 main credit bureaus (Equifax, Experian, and TransUnion) and each has a different credit report on you.  You need to pull all 3 and some services like Equifax will do that for you.  You also need the score.  Without the credit score it is hard if not impossible to tell exactly where you stand.  Some blemishes or dings in your credit are worse than others and some, like preapproval inquiries mean nothing.  So it is best to have the same source like Equifax do this for you.  You can even join a yearly credit watch program where they will monitor your credit and notify you of any problems and provide you with toll free support - that would be my recommendation.

Regardless, once you have your credit report look for errors and anything that you don't believe belongs there.  You have the right to write a certified letter requesting removal or questioning items or entries on your credit.  Any items that cannot be proven within 30 days of receipt from your request must be removed - that is the law.  So, here is a helpful tip from many credit repair professionals - Send in a letter for each and every negative entry.  The odds are that 80% of the time the reporting party has changed hands many times and the new owner of that account probably will not have access to the original documentation and so the account will have to be removed and updated.  This is how to get a quick boost in your score prior to applying for a loan or mortgage.

But, remember, that does not erase the account or your obligation - if you do really owe it.  The other party can and may still come back and relist that negative account again - that is their right and many collection agencies love to do this.  If they are reporting wrong or even illegal information (like beyond the reporting time (7 years for regular accounts, 10 for bankruptcies and some judgements), etc... then you can take them to court and sue them for $1,000 for each occurance per the Fair Credit Reporting Act.  No one has the right to intentionally misuse and wrongly affect your credit report. 

Another way to boost your credit is to take out a loan at your local bank and make timely payments on it.  Take out a loan that you can easily afford like a few thousand or so.  Don't buy anything with it.  Instead put it in an interest bearing account so that you cut down on the interest you are paying back.  Don't worry about the little bit of interest that you will be paying out to the bank - you're goal here is to get a positive record that shows you can make timely payments.  Make every payment on time and do not pay it off early or you will cut short the benefit of this new account in your credit report.  

So, there you have it - how to easily improve your credit and quickly.  There is no reason why you cannot have a 700 or even 800 beacon score (top credit levels or tiers at current).  So, basically you need to pull your credit at least once per year (preferably 2 or 3X with the current score), check for mistakes and fraudulant entries, send letters disagreeing with wrongful entries, and maybe take out a loan from your local bank to help boost your credit score and report.