The best way to begin is by catching your reader's attention. You can ask a question or give a shocking statistic. Then you want to state your point succinctly and quickly. This is known as a thesis statement. In the end, you want to review your thesis and end by giving your reader something to think about.
These are some very good posts thus far. I'd like to offer a couple of extra tips as well. In terms of writing a strong thesis statement, you may wish to consider using a powerful lead-in that not only grabs the reader's attention, but also establishes your authority on the subject; there shouldn't be any room for second-guessing in your thesis. For example...
"It is clear that..."
"It is evident that..."
"Evidence undeniably supports that fact that..."
Additionally, make sure you don't go off on wild tangents throughout your essay. While it is good and you most definitely should explore a different avenue or aspect of the problem in each paragraph, each paragraph really ought to support your thesis. This ensures you have a unified, cohesive essay... which is something all of us teachers look for.
You've got some great advice, and you have some wonderful resources here at e-notes. Best of luck!
At eNotes, we have many useful "how to topics" for you. Consider visiting a few of these pages:
You might also find it helpful to read:
I've always felt that the easiest part of a formal essay is the introduction (first paragraph) and the conclusion (final paragraph). In the first paragraph you need to grab the readers attention from the first couple of sentences. Don't ask a question, and don't use the word "YOU" (anywhere in the essay). But this is where you introduce your topic. Your last sentence is usually supposed to be your thesis. That means that whatever it is you're writing about--this is where you put it into one strong statement. I can give you an example from my senior writing class. One student is writing his paper on steroids and their use in our world. His thesis statement could be "Steriods have become a major concern in our world today, and it's our job as a society to make sure it isn't a concern tomorrow." Something like that.
Your final paragraph should begin with your thesis statement again, but reword it so it isn't the exact same sentence. Rephrase it a little. Then sum up your main points, perhaps make a suggestion or consider alternatives, etc. Make sure each paragraph you write is at least 5 sentences each.