I have a Babylock and just took some classes with my machine. One of the exercises we did in class was to change the tension by one number and sew a bit (make sure to mark on the quilt sandwich tester block which tension setting you are using). Then when you have used them all, review which setting is the best for your machine. When you change batting or technique, do the same exercise. It will help you set up the machine correctly from the beginning rather than turn the project over and HOPE it's done well.
The teacher also suggested that we should invest in an additional bobbin case IF we plan to muck around with it. Once you adjust it, getting it back to "right" can be difficult.