The purpose of a persuasive essay, of course, is to persuade. This means that the first thing you (the writer) have to do is decide how you feel about the subject and what, exactly, you want to persuade others to do or to think. All your evidence will be based on that decision. No one can write your opinion for you.
For example, if you believe that welfare has gotten out of control, you will want to convince your audience (the readers) that this is true by referring to statistics which prove your point. If, however, you believe that welfare benefits should be expanded because more Americans are jobless, you will need to convince your audience of that by providing evidence of increased unemployment statistics and well as show how many of those jobless people are not on welfare; then demonstrate how they would benefit from being part of the welfare system
In another kind of persuasion, perhaps you believe that the welfare system is corrupt and needs to be changed or modified. In this case, you must demonstrate that corruption and then convince your audience to take action based on the changes you propose in order to correct the problems. Or maybe you believe there should be more expectations placed on those who are receiving welfare benefits, such as working diligently and consistently to find a job. In this case, you will have to find programs like this that have worked (and there are some) and ask your audience to support implementing similar programs on a federal level.
Whatever you choose, your position has to be clear and supportable with evidence. The good news for you is that there is plenty of data on the welfare system and its successes and failures; the bad news is that "welfare" is way, way too broad a subject to begin with and you have to make a decision about what you want to research. The length of your essay and the number of required sources will probably also help determine the kinds of things you can and cannot consider.
A sample topic expressed as a thesis or purpose statement might look like this: While welfare does help people in times of economic crisis, it has also created a class of people who would rather cheat the system or stay on welfare rather than work.
First I would find information to show how welfare began. People who needed financial help were divided into two categories: those who were unable to work and those who were perfectly able to work but could not find a job. Those who were unable to work were given financial assistance; those who could work were given jobs.
Then I would have to find examples of changes to and abuses of that system, and those can be found everywhere. In 2007 in Los Angeles, the following incident occurred:
Lana M. and her husband collected welfare benefits..., claiming they earned less than $24,000. But authorities say Lana M....also owned a liquor store and recycling business. Authorities say, she drove a $76,000 luxury car, shopped at Neiman Marcus and Saks Fifth Avenue and had $147,980 stashed in her bedroom dresser.
Next I would have to prove that we have created a dependent class (see the CNN link below).
If all I want is for people to agree with me, I would have done enough at this point. If I wanted to go one step more and convince my audience that something should be done to correct this problem, I would have to offer a solution (or two) that might help help fix it.
Remember to use persuasive language throughout, as well. Make clear arguments and support them with evidence.
The first thing you need to do is decide on a stance to write about. When I learned how to write a persuasive essay, my teacher told me of three approaches - agree, disagree, or qualify. Agree and disagree are pretty self-explanatory - do you support the welfare system as it is now or not? Qualify is a bit more complex and will be harder to write (and possibly more in-depth and longer, so it could prove beneficial depending on your essay requirements).Essentially it means to agree and disagree with parts and therefore to write an agree or a disagree essay while indicating the specific portions you're talking about. For example, you may agree with the basic principles of the welfare system but think an improvement could be made on a specific approach and base your essay to be persuasive to that train of thought. When determining your specific stance, feel free to write about your opinion if you feel very strongly about it. For me, if I don't have a particularly strong opinion for/against the topic, I either choose to qualify or to do research first to determine which side is easier to write a persuasive essay for.
The next main step and an answer to your question about evidence is research. Google is always a strong first step in terms of basic research and understanding for you. In terms of sources I would actually use for the essay, it may be good to consult Google Scholar instead. You want to make sure that the sources you use are reputable because then any of the facts or evidence you draw from the articles will be better support for your argument. Naturally, you'll want to look for articles that support whatever it is you're saying.
Another consideration may be to recognize the opposing side to your persuasive essay. This is difficult because it can easily go wrong. Done well however, it can be added support because you are showing that as an author, you recognize and have a strong response/rebuttal towards a possible weakness in your argument.