@OldMetalHead Trick to do the back. Duck tape a straight line, use ear lobes, and run the blade to follow the line. Do the back first and then use the clippers with your guide. It will look perfect.

@EarnestEccentric just use your ear lobes for a guide to have a stage line across the back. Use the clippers and when you remove the tape you'll have a straight line.

@EarnestEccentric The back is the hard part. I used to give myself a shape up in between cuts. I couldn't find my hand mirror so I was afraid to do it. I thought of the tape. It was so easy.

@OldMetalHead I usually use a single-blade, double-edge safety razor. Multi-blade cartridge razors are fine in a pinch, like when I'm traveling, but they tend to wear out more quickly (which is counterintuitive, but the first blade still does the majority of the cutting and once it starts to dull even slightly it pulls the hair — and the skin with it — so the subsequent blades make microscopic cuts into the skin, causing irritation and making ingrown hairs more likely). I've used the same safety razor since I was 14 years old, when Gillette sent me a free razor for my birthday. (How I ended up on their mailing list, I don't know.)