Some tips from someone who has tried and failed many times to write a fiction story of my own so take them with a grain of salt.

You have to love your own story otherwise it will become a chore and you will give up.
Don’t feel like you need to spell out everything for readers. Keep them guessing
Some of the best writers have very simple and straightforward sentences. Don’t try to be Vladimir Nabokov.
Make writing part of your routine and don’t skip days.
Before starting set some milestones for yourself and then stick to them without fail.
Always use active voice
It’s fine to take a break when needed
Worry about editing later, that’s the job of a good editor and not a writer

My answer is based on the only of my own stories & audio-adaptations, which are appreciated at all:

1: Learn the so called author 101, the basics of writing, grammar, and WHY readability is mandatory.
2: Practice a bit to either form your free flow, or follow the academic formula of structured approach.
3: Learn from your ordeal, as in example the kinda writing you excel with can be more important than the newbie longing (maybe you loved novellas, but your readership only appreciates your flash-fiction length, or full novels instead.)
4: Do some copycat stuff, so you learn to fluff-up and rewrite stolen ideas into a legal version, but do not mistake such for real writing (any ghostwriter does more).
5: Find the mandatory balance between marketing, time for yourself, writing, and maintaining your readership.
6: Survive, enjoy, boast with all the bestsellers, which I certainly will never outmatch. ;-)
7: In the long run staying true to yourself (your writing style, genre, characters) will at minimum create a secondary readership. Learn to handle the money aspect AND the readers you care about. Repeat, what I wrote as 6: ;-)

I recommend a book that calls Poor Dad and Rich Dad

My pick would be The Assassini by Thomas Gifford. I didn't pick this book up because I'm a Dan Brown fan or anything, but because I was really into the Assassin's Creed series of games by Ubisoft and wanted to read something along those lines. My copy of The Assassini had a blurb on the cover that the book is a conspiracy thriller "as shocking as The Da Vinci Code" so it should be a good match for your taste. The story is about a secret society who are in control of murdering anyone who seek to uncover the deepest secrets of the church. This brotherhood of killers used to protect the Church back in ancient times, but nobody knew that they were still very active and still doing their jobs. A lawyer called Ben Driskill uncovers their existence when he investigates the death of his sister, who was a nun. Since the church appears to have no interest in uncovering who the killer of the nun was due to her being a bit of an activist, Ben takes matters into his own hands. The book didn't quite scratch my itch for Assassins Creed style action, but if you liked The Da Vinci Code I suppose you'll enjoy The Assassini.

Read Laughing Gas by P.G. Wodehouse, it's extremely funny. It's very old, but it does feature the golden age of the film industry. One of the characters, Reggie, is an English Earl who is sent to Hollywood to find his cousin and bring him home before he does anything stupid, like marrying an American gold-digger. This goes pear-shaped when Reggie has to go to the dentist because of severe toothache, only to wake up as a 12-year old movie star called Joey Cooley. The two somehow switched bodies when given anesthetic. Reggie finds that the life of a Hollywood brat is not all that it is cracked up to be, while Joey uses his new grown-up body to get back at everyone who wronged him.