Dustin hit the nail on the head.
Just guide the line into the blade and take your time and you will be amazed at what you can do.
A hint....Curved lines are easier and a lot more fun to cut than straight lines. No kidding, it is not all that hard, it just takes time to cut what "look" to be very difficult patterns.
Relax, breathe, make sawdust and enjoy your time hunched over the noise maker.
Rog
PS. Al W had a very good suggestion too. Check out Steve Good's main blog, he not only has hundreds of patterns but he has a bunch of videos and teaching aids also.