It sounds like you already know how to press since you can tell that some if not most of the video instructors are doing it carelessly. I agree with you, I always notice this and I think it leaves an impression that you can get by with that. But as you say, when you do it that way, you get bad results. However, I do think if you know which way the grain is and you iron with that you can be a little more laxed. Someone above mentioned signing up for the Craftsy free block of the month lessons and that is an excellent suggestion. Learning the basics correctly saves a lot of frustration later. Good luck.