I'll offer my two cents as a centrist liberal.

I did my undergrad with law school in mind, so my approach to essay-writing was, whenever possible, to argue the opposite position to the one I held. I thought - and I was correct - that this exercise would be ultimately beneficial to me as a law student and eventually, in practice.

You don't have to believe something to argue it effectively, you just have to know your shit. The key is to keep an open mind, do excellent research, and edit edit edit. Always write in your own voice. I maintained a near perfect GPA throughout my undergrad mainly on the strength of my papers, and from what I hear, some professors are still using a few of them as examples.

Most importantly, though, I think that taking this approach not only helped me to learn and understand positions that are not my own, I can also anticipate arguments much more easily than I think I could have had I not employed this strategy when I was young.

Short story long: approach this as a skill-building exercise. It will pay off, I promise. The first few times you might feel like a fraud and a phony, but you aren't. You're learning and making the most of your opportunities.

Now get out there and do your worst, and I'll see you on the battlefield :)