stop spamming the extra spaces—the em-dash does not get spaces around it--and if you are using plain ascii, or a typewriter without a dash key, it's standard to

stop spamming the extra spaces—the em-dash does not get spaces around it--and if you are using plain ascii, or a typewriter without a dash key, it's standard to just use two hyphens. The time I think it's best to use an em-dash is if you have a parenthetical (like this one) but you feel--because it is off the main subject--that it is too strong a thunk in the middle of your sentence, the em-dash streamlines it. Rather than learning to type it in different contexts, I just stick with the double-hyphen approach.