A big problem with theft deterrent/prevention methods is that people don't use them. A successful theft deterrent has to be something you will use every day, so that on the day a thief comes by looking for a bike, it won't be the day you were in a rush and didn't lock up.
Just steering lock: pointless. youtube videos show people breaking those without any tools at all. Then they can just drop it in neutral and roll it away.
Disc Lock: By itself is no good, as a bike can be picked up into a van/pickup/trailer very easily.
Chain to a post/sign: Kind of a pain trying to find a sign close enough to lock to without a lot of hassle.
LoJack: Doesn't prevent theft - just helps recover and catch thief.
Cover: Out of sight, out of mind. Hard to case out a bike if you can't see it without touching.
Here's what I use. I got The Bike Barn for free on craigslist. Somebody was moving and didn't want to go through the hassle of selling it. Now that I have one, I wouldn't want to go without. It's just a tent for a bike, but it's much faster and easier to use than a normal cover, and you can cover the bike up while it's still hot.
I got a Bully 5'6" noose chain and a 13mm onGuard disc lock. When parking not at home, I use just the disc lock on the front disc. When parking at home, I chain around the rear tire to a post. The chain is the ONLY chain I was able to find that was both 5 feet long AND had a noose end. And it was only $50! The noose end allows you to use the full length of the chain to attach the bike to a post. Much easier than having to carefully move your bike close enough to get a chain to fit around. The risk is that with a longer chain, it is easier to cut or break it. Really any chain can easily be cut with a portable angle grinder, so I was willing to take that risk. The 13mm disc lock was the largest lock that would fit in the links of the chain, and it's fairly portable for on-the-road use.