Go ahead and try 2 strands! It is super easy and gives everything a really neat look.
And I second whoever made the comment that you can play with color combinations and types of yarn too. I've done scarves with fun fur and other types of yarns and gotten RAVE reviews. In fact, that was my second project after learning to knit was to knit a scarf with 2 types of yarns together.
The worse that can happen is that you don't like it and you rip it out! :D
Good luck! Just yell if you need help!