I am trying to deserialize an old file format that was serialized in Delphi, it uses binary seralization. I know nothing about the structure of the file except some very high level records that are in it.
What steps would you take to solve this problem? Any tools etc?
A good hexeditor, and use the gray matter to identify structures.
If you get a hint what kind of file it is, you can search for more specialized tools.
Running the unix/Linux "file" command can be good too (*) See Barry's comment below for how it works. It can be a quick check for common filetypes like DBF,ZIP etc hidden by using a different extension.
(*) there are 3rd party builds for windows, but they might lag in versions. If you can do it on a recent *nix distro, it is advised to do so.