I really like your quilt! The design is just great. I think the idea of straight line quilting is a great place for a 'beginner' to start. For one thing, your stitches will be regulated and even because the feed dogs are engaged.
There are lots of ways to determine your lines for stitching. You can use painters tape or tiger tape and move it from place to place. You can draw with Crayola Ultra clean markers and just wash it out. If you use red thread in the red, blue in the blue and white in the white areas, the stitching will show the quilting but will not be obvious enough to show any 'bobbles. Your quilt is really pretty and the piecing looks so nice that I am sure that you will do very well with the quilting. Please don't be fearful-just jump in and do it. Don't forget to show us again later.