Helix, Help Please

I received my helix today and have been reading the posts whilst I waited for it to arrive. I have tried to find my 'sweet spot' in the meantime and am still not really sure if I've found it. I've found a few spots along the muscle between the base of my erection and my anus that feel different from the rest of the area, except pressure feels more uncomfortable than pleasurable.
Now that I have got it inside me it seems best with the tab on the spot closest to my anus (slightly the more pleasurabe spot of the ones I've found, nothing special though) except as I contract, lube ozzes onto the tab cos the spot is literally just up from my anus. The other better spot I've found is quite close to my balls and putting the tab there almost pulls the helix out. The handle of it seems to stroke one bum cheek as the aneros moves in me, I'm not sure if that means it's off centre or just that I've got uneven cheeks!
Also not really sure about the best way to contract it. Which muscles? How hard is hard and how hard should the baseline contractions be? I can feel my anal contractions I think. What exactally are the involuntaries too? If I contract to about medium strength then my muscles eventually spasm slightly and this kind of vibrates it inside me, if I then rock my hips slightly it feels really nice but the tremors seem to die down without me changing what I'm doing. We're (a couple) fairly experienced with anal playing including plugs, prostate massage, beads etc which all feel good but have never had explosive ends alone.
I am excited to have found the helix, I'm sure it's going to be alot of fun learning all about it's benefits. It felt really good inside as soon as it went in so I'm sure we'll enjoy the ride.
Hope someone can help us out.
Thanks,
A newcummer (maybe!).