Good techniques for influencing people include framing, timing and interchanging services. Other ways to persuade are to use confident speech, imply a shortage, and refer to influential people.
To persuade someone by framing a subject, think of words that have positive or negative emotional associations and use them in your argument. For example, the phrase "inheritance tax" sounds positive, but those that dislike it call it the "death tax." Practice good timing by waiting until the person you want to convince is mentally tired. It is then easier because they are less interested in a conflict.
Practice interchange by doing something nice for someone. Later, reference that good deed when you need a favor because the person may feel they have to do something in return. Use confident speech to be more persuasive. Be direct, and try not to say "uh" or "um."
Advertisers often imply a shortage to get consumers to run out and buy a product. Before trying to convince someone, think of how the situation would be affected if a good or service were lacking and use this as part of the argument. Also, people are more likely to follow along with friends, family, or influential people like politicians and celebrities.