There's a very complete article on the subject in the Knowledge Base:
Be prepared to work on the converted databases to get them fully functional. It's often the case that you hae to make a few adjustments to your scripts and you may have to clean up some data if you have text fields used as keys that no longer seem to match values like they did before. You also often find a lot of convoluted external file references if your files have links to each other. Older versions of filemaker didn't handle such references very cleanly, but at least with newer version, you can see and edit them to clean them up.