Creating A Portable App from Scratch

There are a lot workarounds used by John for Apps that use the registry or store data in various places to keep them compliant with the specs used here. But the less we have to use the better.:)
If you do an Application from scratch the best thing regarding compatibility with PortableApps.com would be if it wouldn't write to the Registry and have a switch to pass the path where the config files are located.
That would be the easiest Application to make portable.

Hope that helps and welcome here

If you are only writing a program to be portable, using a command line parameter to tell it where to put its settings is ideal. I suppose you could have it save to the application's own directory if there is nothing on the command line.

If you want it to be either portable or installed, it might be a good idea to have the default place be appdata. Or have it use the Registry unless told otherwise on the command line. It can be awkward for a regular program to save things to its own folder.

The important thing for portability is that there be an easy and unambiguous way to tell the program where to put its settings and/or data that keeps it from writing to the registry or appdata or My Documents.