I think seeing mating nets in practical play requires, for most of us at any rate, a lot of repetition to ingrain certain positions and themes into our heads. One thing you can do is to study mating patterns so you know what to look for or to aim for. Here are some classical ones.
Other ways are to work problems and puzzles and play over master games. Games by older player such as Adolf Anderssen, Paul Morphy, Harry N. Pillsbury for example often demonstrate practical mating themes. Games from more modern players usually just hint at those things since the advanced defensive play usually predicts and avoids them.
I doubt there are any tricks, just a lot of work.
Are there any practical exercises, or tricks of the trade, that improve one's ability to see "mating nets"?