For those looking to try double edge shaving, the proper angle to hold the razor is the big question. For the proper angle, Google "vintage Gillette instructions". You'll get at least three illustrations, which appear to show the handle held at 45 degrees to the face.
For Youtube videos, they should be taken with a grain of salt. Some show long strokes like a cartridge razor. For DE, short strokes are best. Also, keep the skin taut and as much as possible, try to let the weight of the razor exert the pressure against the skin.