We've never had any trouble keeping deer out with an electric fence with one wire about 18" from the ground and another about 36". Using the thin wire and not a ribbon, I don't think they can really see it, so it zaps them and they don't know where it comes from, and they can't see what to jump over.
To keep crows out, put a stake about every 50-75 feet, and criss-cross white twine between them, basically making Xs in boxes. Crows will walk up to the twine but not go under it. The theory is that they are afraid that if they go under the twine they will get tangled in the twine if they need to fly away quickly.
Without using an electric fence I've had some success keeping deer out with just twine, putting the strands at 18" and 36" and adding the criss-cross for the crows. They push against it though and if the twine is rotten and breaks or a stake isn't in really well and falls over then they get in. Deer don't have great depth perception so I think they don't jump over it because they don't know how far away the criss-crossed lines are. That's also how a double fence supposedly works. Another way I heard will work is to put short horizontal bars at the top of the posts with a line on then end to create the illusion of a double fence.
I remember my dad trying the irish spring soap once. Every week the uneaten circle around the soap got smaller and smaller.
I don't think predator scents work all that well, at least not with bucks. I've gotten trail camera pictures of bucks and coyotes together, and the bucks didn't seem bothered by the coyotes. I also shot a buck a couple of years ago that walked between two coyotes I had killed 30 minutes earlier. Does, especially does with fawns, will spook from coyotes though.
Urine doesn't work that well either, in fact there are some who will use urine as an attractant, making a buck think you're a buck challenging his territory.