Credit reports look intimidating. They're really just five sections.
Personal information Name, addresses, employers. Errors here are common and worth disputing — they're a common vector for mixed files.
Public records Bankruptcies. (Judgments and tax liens are no longer reported.)
Trade accounts Every credit account with its own status, balance, limit, and payment history grid.
Collections Third-party collectors with the account, amount, and status.
Inquiries Hard and soft pulls in the last two years.
Read every section. Flag anything you don't recognize or that reports incorrectly. That flagged list is the starting point for any dispute strategy.