Choose a broad topic, then, by researching it, narrow down the thesis statement. For example, start with the broad topic of "fossil fuels" and narrow that topic to "use of fossil fuels by large corporations."
Take a position on the topic that can be argued. It is important to have a position that somebody might reasonably disagree with. This will give the paper a persuasive aspect. For example, the above thesis could become, "Large corporations should cut down on the use of fossil fuels."
Use facts to back up the thesis. For example, given the statistic that large corporations use 90 percent of available fossil fuels, a statement could be: "Since large corporations use 90 percent of fossil fuels, they should be required to cut back on their dependence on fossil fuels."
Test a thesis to determine whether it takes a stand. A statement such as, "There are pros and cons to all-night bowling" is an example of a weak statement. "All-night bowling is detrimental to the community" is stronger because it takes a stand.
Be specific. "Tornadoes are devastating forces of nature" is true but not specific. "The tornado that twisted through a small town in Oklahoma on March 13, 2011, at 12:13 p.m." is much more specific.