How to add query-string parameters to plugins?

I’m developing a plugin which adds a new function to the template.

What’s the best way to provide query string-style parameters to the plugin? It’s easy enough to add parameters as standard arguments, or through an array, but I can’t find any good documentation on how best to handle query-string style parameter passing, which would obviously be useful before freeing the plugin. Standardising behavious is very important for end-users.

Can anyone point me to up-to-date documentation or examples of best practice? Failing that, any examples at all?

TIA, Dave