I shave with a Dovo Full Hollow Ground black nickel 6/8″ straight razor, and before every shave I’ll strop it on leather strop, with some Stangen strop paste. Just like this.
It’s easy to do and takes no real skill. You lay the razor flat, draw it across the strop spine first and turn it over, then go the other way, and remember a slow pass is just as good as a fast pass. It’s not a race. Obviously you’re not sharpening a blade with a strop, you’re just realigning the blade and taking off any burs. When a strop isn’t enough you can make a few passes on a honing stone, and when that fails, then you’ve got to sharpen it, although a lot of barbers, like chefs, send them off to be professionally sharpened. But I think that’s stupid because it’s not difficult to sharpen a razor.
A straight razor is hollow ground i.e. it’s concave coming to a fine delicate edge, so it’s easy to fuck up on a whetstone, waterstone or a grinder. But you can sharpen and hone it with sandpaper: sharpen it on a 1k grits, hone it on a 4k grit and polish it with a 6k grit, stroking the blade across the paper just like you’re stropping, and spray some water on the paper. You only need a few passes on each grit. But don’t do it to often and put some electrical tape on the spine of the razor to protect it, because otherwise you’ll grinding the spine, but you don’t need to worry about that on a strop.
Can you use a strop with a normal knife I hear you ask. Well as it goes, yes you can, just a couple a couple of passes after you’ve ground the edge will take the burs off and polish it. But if you do it like you do a razor dragging it spine first, you’ll end up with a concave bevel angle. So use it like a grinding stone: tip to heel at a 20º angle (or whatever your bevel angle is) against some leather on a hard service. I’ve got a proper barber’s strop hanging on the bathroom sink because I use a straight razor, but you could get away with using an old leather belt as a strop.