Many ways you can do this. I'd suggest that you temporarily place sub where you will sit and while it's playing some suitable bass material crawl around in some of the likely final positions and listen to the quality of the bass you are getting as you move. When you find a spot that sounds good, place the sub there. This location should be away from corners. Corner placement tends to make subs sound boomy and ill defined.
Next, you should set the cutoff frequency at or below the point where roll off begins in the mains. This is usually in the 40 - 120 hz range. I normally get better results at settings closer to 40 hz. Set volume just below where you can hear and localize the sub. The volume should be about the same level as the mains. If the sub has low pass filter options set it to the highest setting, generally 12db or 24db to prevent the sub playing into the mid-range.
Finally, I'd buy the Auralex Subdude to place under the sub. It's not entirely necessary but it will help get you a tighter and punchier bass and only cost about $60.
Next, you should set the cutoff frequency at or below the point where roll off begins in the mains. This is usually in the 40 - 120 hz range. I normally get better results at settings closer to 40 hz. Set volume just below where you can hear and localize the sub. The volume should be about the same level as the mains. If the sub has low pass filter options set it to the highest setting, generally 12db or 24db to prevent the sub playing into the mid-range.
Finally, I'd buy the Auralex Subdude to place under the sub. It's not entirely necessary but it will help get you a tighter and punchier bass and only cost about $60.