Persuasion is an art, and the strength of an argument is largely based on the persuasive words and phrases that are used. The most important words and phrases to use are those that convey knowledge and confidence and avoid indecisiveness and uncertainty.
For example, one should never use the phrases "I think" or "I guess." This demonstrates uncertainty; instead, use phrases such as "I know," "from experience I can tell you," or "it's a fact that..." The message should be delivered as forcefully and confidently as possible.
An argument should also be directed at the opponent or audience using the word "you." When the word "you" is used, it involves the opponent or audience in a personal way. An example would be the phrase "My view is the better view, and it will make your life better." If the opponent or audience is made to feel that adopting a particular view will benefit them in some way, they are more likely to accept the conclusions.
Another strategy is to use words and phrases that address the counter-argument. If a position is being argued for, the counter-argument should be addressed and revealed to be inferior to the position advocated by the arguer. Some great phrases to use include: "I used to think the same way as my opponent, but then I learned...," or "position X will lead to undesirable consequences, but my position avoids all of them."