The most important thing to remember is that the upper crossover point on the sub needs to be "below" the start of the roll-off point of the speaker's woofer. Most people set that too high. Take a look at the typical graph below. This shows the individual speaker measurements and the total resulting frequency (red line) as they sum each other. You've probably seen this in Stereophile many times. I think it depicts what I said above rather well. You can set the sub crossover lower than you think, then adjust the volume of the sub until things start to gel and balance out. You will likely tweak the crossover and volume and sub phase over the next few days/weeks using different recordings until it all balances out to your ear. Of course, using a meter will help, but your ear is the final judge.
Next, putting a sub in the corner is what you may read in many articles about set up, because you have reinforcement from 3 surfaces ... the 2 walls and floor. That works fine for movies with dinosaur stomps but not as well for music. I found pulling the sub out into the room and placing it next to the speaker works best for music. It might have to be turned up louder there but it will sound like it integrates better in that position.
Third, I also believe in taking away all boundaries helps, even the floor. For instance, I have my down firing sub placed upside down with the feet pointing up. This raises the sub's speaker off the floor. You can do the same with front firing subs by placing them on some kind of support stand or sturdy cement block. Getting it up off the floor works best for me and my panel speakers. The sub sounds "faster" and integrates better.
Most of all, experiment. I heard in one instance someone say to place the sub where you normally sit, up on the chair, then get on your hands and knees and move around to likely placement positions and listen with your ears. If you hear boom then that's not the right place for the sub. Somewhere it will all click in. Then move the sub to that location and begin dialing it in. Ingenious idea and it could work for you because it identifies room nodes better than the usual trial and error.
It will take time to dial in so listen to plenty of music and have fun with it.
Good luck.