Add some quirks and weaknesses to your protagonist - they are human and not divine.
Try to avoid the cliches though -there are too many in modern fiction who have problems with alcohol, are divorced and have a teenage child (usually a daughter).
It's alright to have passion for something but don't lecture the reader on it. If you, as a reader, don't like Jazz you don't want pages on the music (it happens 🙁).
It's alright for them to have self-doubts, it allows the reader to feel their concerns - they are not superhuman.
Think about a sidekick/partner (Batman/Robin; Robin Hood/Little John; Morse/Lewis; Holmes/Watson) but maybe your hero is a lone wolf (Bond; Reacher).
How evil should you make your antagonist? Are they ruthless, psychopathic, or just bad and without a moral compass? Fleming preferred megalomaniacs but others write characters who just see things from another perspective - loyal to their own county or people (Don Corleone).
Put your hero into a situation that seems doomed but write a realistic escape. The cavalry arriving in time but set the cavalry in motion well before the incident so they are not a total surprise. Or the hero talks out the danger (Bond/Goldfinger and the laser). I have a serious doubt that handcuffs can be unlocked with a paperclip.
Who else is in the story? What is interesting about them? Boss (M), lover, mentor.
Characters should have a backstory to explain their current skills and mindset. It can be experience (Armed Forces) or a trauma that moulded them.
In my book "The Bootlegger of Illinois", my protagonist (Jesse) wants to save his farm, served in WW1 as a sniper (attending a specialist training centre - which happens to have actually existed), so he has motivation and survival skills. He can rely on Sheriff Tom Buckley to have his back and loyal workers on the farm who also want to save it. The antagonist (Sean), in Chicago, is not immediately an antagonist but Jesse has something he wants - Jesse is distilling gin during Prohibition. Sean is not so lucky with his gang members and a negotiation goes wrong ( the central plot). Sean is ruthless but also pragmatic and has a decent side to him, with charitable acts and faithfulness to the woman he loves. There are mini stories to present this facet of his character.
It can help to write prompt cards to oneself, for each main character. Physical description, back story notes, habits and favourite items. That way you are unlikely to contradict yourself.
Now get writing.
Credits
Written by Keith Lawson
Photo by Suzy Hazelwood
