TIPS

Try to think of a creative vow and write it down. Make it something like: I vow to give at least one compliment to someone each day and I'll try to control my anger by counting in my head before reacting.
Don't think of happiness as a mood, but as a philosophy of life. It's a frame of mind, a way of re-adjusting your thoughts, not something you "feel" all the time.
Be patient, as trying to achieve everything within twenty minutes, or just a day, may not work out as perfectly as you guessed. Committing yourself to this lifestyle takes some serious reflection and perhaps, change within yourself, which will take longer periods of time - so wait for the changes, as they will be worth it.
Don't let others drag you and your lifestyle down. If somebody treats you badly, let them know that you respect yourself and therefore they should, too. Don't let other people decide how your life will go, because you know that's not their choice to make.
Make a CD or playlist of songs that make you feel happy and listen to it when you feel down.
Protip: You could follow the mantra that all things are one and exist in perfect harmony that only increases in value over time. In this worldview, to call anything "unnatural", "sinful", or "evil" is to create a division only within yourself, not within nature (or God). The 3 keys to happiness:
Know thyself
All things in moderation
Reach for the stars
Stop trying to be happy. Nobody ever finds happiness for long; it finds them.
Have some kind of release.