One big mistake I see a lot of writers make, especially in the nonfiction world, is they hedge with their statements. The write phrases such as "He seemed truculent," or "He was a powerful man with large arms, a wide girth and penchant for bullying the needy, I think," or "She could be lovely."
There are problems with these phrases from a show, don't tell perspective, but the point is the writer or person making the statement is hedging. Don't write that someone seems something or that you think they may be something or they could be. Strengthen these sentences by declaring them to be true.
The person in public life who does this the most is John Kerry and it drives me crazy. He never makes a declaration, it's always in my opinion or I think or some such thing. Listen for it when he speaks and you'll see it.
There are exceptions, but they are few. For the most part using words that hedge on a statement only fattens and slows the sentence and doesn't tell or show the reader that they need to be convinced the big guy is a bully.