Introductions to essays are sometimes the most difficult things to write because there are still so many uncertainties about an essay that has not yet been written. In fact, I often write the introduction last when I am working on an essay. That does not mean I do not have a plan; I can write an essay without writing the entire introduction first if I have a clear statement of purpose or thesis.
So, that is where I might start. Make an outline of the key issues you plan to discuss in your essay and then put those points into a one-sentence purpose statement from which you can write, complete introduction or not. This statement is the most significant thing in your introduction anyway; the things you will use to add interest can be added later.
Make a list of the "pros and cons" of social networking (of which Facebook is a part) and go from there. Perhaps you will conclude that social networking has more advantages than disadvantages. If so, your thesis might sound something like this:
- Despite some potential risks, social networking is a positive component of society when used wisely.
If you believe the opposite is true, this may be more like what you should say:
- Though social networking does have some benefits, it is a dangerous tool and should be avoided.
Obviously there is room for some kind of middle ground, and you can certainly add some specific points to each of these sentences to make your point of view even clearer for your audience.
A meaningful topic will tap into underlying values and issues of modern society. Look for the themes or big ideas of your issue.... Seeing the “big picture” adds depth to your argument.
Once you have determined your purpose statement, you can either write the introduction or you can continue writing the rest of the essay and go back to the introduction. Remember that an introduction is your readers' first impression of you and of your position, so find an interesting story (your own or someone else's) to share, a startling statistic (which should not be difficult with your topic), or some other creative way to prepare your readers for your argument. Often it is possible to connect your conclusion to the introduction, as well, for greater continuity and cohesiveness.
I have attached an excellent eNotes site which offers some practical advice on writing a persuasive/argumentative essay. Happy writing!