Every person who quilts has to decide his or her level of acceptable vs. perfection. I would agree with all of those who have suggested going to a LQS for advice-I have always found them to be helpful when they realize that you are sincere. There are lots of youtube tutorials and Craftsy classes. I have enjoyed several Craftsy classes. I admit there they have been a couple that did not live up to their billing or to my expectations. Something that might be of help to you to see what you problem might be is to make paper templates. Use graph paper so that you can really see the detail. Make the templates just like the finished sections of the HST or flying geese is to be. After you cut the fabric compare it to the template to see if it is cut correctly. If not correct, look at your ruler-are the lines too wide, etc. Make notes as you go. If cut correctly, stitch the first seam and compare it to the template. Does it match, is the seam even and 1/4 inch. Make adjustments to the foot you are using, the guide you make for yourself-sticky note pads, moleskin or whatever. When your seam is correct go to the ironing board. Do you set the seam? Do you 'press' or do you 'iron'. To press you set the iron down on the work and not pull in any direction from the seam. If you pull you will distort the patch and it will be wonky. Compare your pressed patch of multiple pieces to the paper template. If it is off you can determine if the pressing is the problem. Because you are dealing with angles-bias and otherwise- you have to be careful. I think starch is a good help but it really does not substitute for accurate technique. This exercise could be well worth the effort. It will help you understand the why of a problem.