There are plenty of folks on this forum who can sew far better than I can. But for those of you who struggle a bit (like me), I figured out a way to sew MUCH straighter lines. Set your STITCH LENGTH to SHORTER. This makes the fabric move MUCH SLOWER through the needle. The needle is still zooming, but the fabric moves much slower (still walking fast, but taking smaller steps) so the fabric is much easier to control.
I think Ramblin' Rev and other experts will agree that one of the differences between a cheap TI and an expensive one is the clutch mechanism. On my cheap TI, I have to really "hit the gas" to get going or else it bogs down. I can help the fly wheel get going, but I don't usually have a spare hand. This "jack rabbit" start can be hard to control, but short stitching makes the fabric move much slower. Plus, to my eye, tiny stitches look more professional.
Just an "Ah-HA moment" I wanted to share.