2nd Deadly Sin:
Sewing with the wrong top tension setting
Having too tight top tension will create uneven stitches and can cause your thread to break. Machines with automatic tension settings are often set too tight. Manually reduce the tension (this means override the automatic tension settings) and always go lower than you think it should be. It’s much easier to over-loosen the tension and slowly tighten it up than it is to drop the tension in small increments, have the thread break, re-thread, lower tension, thread break, etc.
The top and bobbin thread play a tug-of-war with each other when sewing. If your bobbin thread is pulling to the top, even if the top thread isn't breaking, you top tension is still too tight!
Give yourself (and your thread) a break and loosen up that top tension.