Source includes 2 more common sense tips:
5. Don't apply for too many cards at once
7. Don't Lie about Credit info

You should check your personal credit report at LEAST twice a year. You are entitled to 1 free report from the 3 major credit bureaus, free of charge. The other you buy, no big deal, it's worth it.

The reason you want to check it TWICE a year is due to the possiblilty that something will be added to your reports and you won't see it in time. If you are checking twice, you chances of catching bogus entries are greater. This happened to yours truly and I learned my lesson the hard way- you don't have to.