I found that to practice simple designs like leaves and hearts, get a stencil for a simple border.
Practicing on the border is much easier since you dont have a folded up quilt in the throat of your machine.
For the body of the quilt do a simple straight line design with the walking foot. You can use the attachment that will give you even spaced lines or stitch in the ditch.
There are many different marking tools, sometimes I use chalk and pounce and sometimes I use a dissapearing ink pen.This is something you have to experiment with till you discover what you like best.