To make your writing more powerful, always know what the need is of each character. Something specific - not "to be a winning driver" but "to win in the Regional finals." Not "to be rich" but "to be worth $1 million by the time I'm 35" or "to live in that house." Rocky Balboa didn't expect to win the title, he just wanted to be still standing at the end of the bout. You don't even need to tell the audience what each character's need is ... just so long as you know it, and make it the driving force behind the person's actions and dialog.
Some Past Writing Tips
There aren't very many absolutes in screenplay writing ... as long as you get the format right, fix all the spelling errors, and don't exceed 110 or 120 pages. But one guideline that always helps a script get the attention of an agent, producer, director or actor (or the story analyst that any of these is likely to turn the script over to): see if you can get the story started so that something unexpected, unusual or shocking happens on the first or second page.
Nothing is guaranteed ... but manage this and you can at least expect that the reader will likely get a few more pages into the script than otherwise.
Story analyst and would-be screenwriter Glynis Ahearn listed some pet "uh-oh's" in a recent issued of "Written by," the magazine of the Writers Guild West. Among mis-steps she has found in beginner's scripts: Naming the central character after yourself. Putting your name in the title, as in "John Warren's Wild River." Starting a flashback on the first or second page. Remember that the viewer won't know what's in the action description; don't tell about the characters there in ways never revealed in dialog or action. Don't plagiarize - industry people tend to know movies well enough that they're likely to recognize what you've stolen. And don't smoke so heavily around the script that it's delivered smelling of smoke!