[font=trebuchet ms]Welcome to the GT Forum!
At the risk of stating the obvious, the first thing you need to do is develop your sense of rythym. Mute the strings with your fretting hand, and let your strumming hand experiment freely with different patterns. Think in terms of providing a percussion accompaniement for the melody. Throw in some variations instead of just grinding away at one 'chuffa-chuffa-chuffa-chuffa' sequence. Above all, have fun with it! :D
After you have some skill in accenting the beats, you can try shifting the emphasis across different strings to alter the voicing of the chord you're playing. More fun.
This a chance to set the rules instead of reproducing or interpreting someone else's work. Enjoy![/font]