When I need to be spot on such as with points, I try to make sure the those points are on top so when I come to them during the sewing process I can nudge over so that I'll sew right at the tip as I should. If I can't do that then I take a disappearing pin and mark where I need to have my needle go on those points on the opposite side or the side I'll be viewing when sewing. Either a disappearing pen or chalk or whatever you use to mark. When I'm sewing 2 points together I'll stick a pin thru to both sides making sure they meet as they should then pin on both sides if neccessary of the point. You're not the only one that cuts their tips off when sewing so don't be hard on yourself.