"It is considered not good practice." vs "It is not considered good practice"?

Solution 1:

First, as a peripheral issue, you really need a comma after "to", as the rest of the sentence is a separate dependent clause.

As regards your main query - the two forms do get used interchangeably.

However if you think about it logically, they mean slightly different things. "It is not considered good practice" means no one considers it.

But "It is considered not good practice", means that people do think about it but take the view that it is not good practice.

But for all practical purposes, "not considered" is perhaps just a slightly less emphatic way of saying the same thing as "considered not".