Jeff Hader over at Inc. has compiled a list of words that are often used incorrectly, particularly in business communications. The list is full of good advice about usage of common words. For instance,
"Impact and affect (and effect)
Many people (including until recently me) use impact when they should use affect. Impact doesn't mean to influence; impact means to strike, collide, or pack firmly.
Affect means to influence: "Impatient investors affected our rollout date."
And to make it more confusing, effect means to accomplish something: "The board effected a sweeping policy change."
How you correctly use effect or affect can be tricky. For example, a board can affect changes by influencing them and can effect changes by directly implementing them. Bottom line, use effect if you're making it happen, and affect if you're having an impact on something that someone else is trying to make happen.
As for nouns, effect is almost always correct: "Employee morale has had a negative effect on productivity." Affect refers to an emotional state, so unless you're a psychologist, you probably have little reason to use it.
So stop saying you'll "impact sales" or "impact the bottom line." Use affect.
Read about 38 other words that are commonly misused at Inc.