Don't watch the needle...look just at the stitches just a bit in front of the hopping foot (or whatever direction you need to go in), and this will help.
Try it on paper... can't draw a straight line on paper? Try looking about an inch in front of the pencil as you draw...your hand will follow your eyes...and you will be surprised how good you can draw a line after a couple of tries.
On feathers, unless I'm doing the hump/bump kind..I just stay close to the past line...and don't worry about keeping the next feather exactly on the line of the last one..as long as you are consistant in how you do them...won't matter...you will see how great they look that way. Again, if you are trying to stay right on the line of the last feather, don't look at the needle...look at the line of stitches you are going over...just a bit in front or back of the hopping foot...your hand will follow where your eyes are looking.
I was wondering if any of our long arm folks on here might be willing to help me. I am still learning. One of the things I am trying to do right now requires going back over stitching. (back stitching) I was wondering if you have any tips for staying on the stitching. Seems like I keep getting off of it. I know it wont be perfect but I am hoping for better than what I am doing. Thanks in advance.