Best practice: Howto update/modify a patch?

Hi!

From time to time I get in the situation to update/modify an existing patch. When I use `devtool`, the old patches will be applied, and results in an additional patch. The newly created patch modifies the same code area(s) as the old patch(es). OK.

So, I wonder whether there exists best practice to update/modify an existing patch?

Thanks for any hints.

BR, 
H. Wulff