"Politics" may be a very personal matter. No matter what country or region you live in, politics can play a large part in your outlook on life.

[edit] Steps

Learn about the Liberals whether you think you might agree or disagree with them. Watch the news, read books on differing views, go on their websites. Nobody will take you seriously if you don't know for whom or on what you're voting.
Be courteous but proud of your political choices. Defend your decisions nicely. Find a few points that you really like, and bring them up whenever the topic turns to politics.
Think what being Liberal means to you. Why did you choose the Liberals over other political parties? What makes them better than everyone else?
Stay un-biased--be fair minded. If you are watching the news, and there is a piece about a Liberal scandal, don't dismiss it saying, "Oh, the Liberals wouldn't do that!". Stay on top of current party events.
Listen carefully to people. They will try to tell you all the bad things about the Liberals while conveniently leaving out all the good aspects of the party. Every political party has flaws. Don't let other people's opinions sway yours. Stay true to your decision.
Don't be afraid of change. Despite what earlier steps state, if you think the Liberals have changed too much for your liking, feel free to adopt other views and support or vote for a different party.

[edit] Tips

The more liberal (or more socialist) party is not necessarily named the "Liberal" party.
Don't bring up politics in a conversation unless you know the other person is willing to talk about it.
Read lots of material about the party.
Don't brag about how much better your party is than others.

Politics can be very personal like their choice and practice of religion, so be careful not to offend people unnecessarily.
Politics and religions often are not that personal to the devotees, but the options may be held in a very outgoing form, and one may want to "convert you"--instead of saying: "Leave me alone!"
Don't get caught up in minute details (20 second sound bites) that the news is focusing on; look at the bigger picture for your whole city, county or country, not just one little aspect.