Considering the output levels of the sub is question, I would condsider corner loading to get the benifit of output that comes with that. Otherwise as close to Lp is going as possible is going to give you the most enjoyable experiance.
LP = listening position. To find the best place for your sub, try the "sub crawl". Place the sub at your main listening position, put on some music with lots of bass, crawl around the room to see where the bass sounds loudest. That's where the sub should go. Google sub crawl for more info. Generally speaking, placing a sub in a corner (any corner) gives you more bass.
Audiophile34 is partly correct. Generally corner loading a sub is ideal, bit from my experience with the hw-e450, it will sound boomy. But you can start by placing it in the corner that's closer to.the sound bar, so you get nice mixing. From there, use the sub crawl, to pinpoint the perfect location. Problem I see with corner loading is the booming effect and the fact the a lot of people have their couch against a wall, which makes it considerably overwhelming.
total noob here.. does it matter which side of the subwoofer faces what? do you want the softer vibrating panel to face the wall/couch? did sub crawl but couldn't tell where the best place for the bass is.. need help please..