Removing any inaccurate information on your profile, and consistently paying your bills on time... Doing these two things go a long way to improving your credit...
In addition, having two credit cards (with balances no more than a 1/3 of your credit line), an auto loan and a mortgage if possible, to show variation in lenders...
If you are asking for techniques on how to remove legitimate items, like charge-offs, judgements, late-pays, etc... there are sites that discuss how you can do this, but if it is legitimate, it will be harder to remove, and can take anywhere from 60-180 days to make any headway... you can visit sites like...
www.creditboards.comIn the interim, pay your bills on time, establish credit (even if you have to start with secured credit cards) while you are attempting to remove the other stuff, as the length of time you have credit also boosts your score...