Wanting advice our new toy is ready to get lubed up and used but don't want to do it wrong help??
There isn’t right or wrong positions, as long as they are comfortable for both of you. If this is the first time anything as large as the strap on has been used, maybe try with the receiver on their back as this will be most comfortable for them or with the strap on wearer on their back so the receiver can have a little more control. This is also a good idea if you have never used a strapless strap on before as it will reduce the chance of the strap on slipping out of the wearer (although this can still happen)
It can sometimes be difficult to keep a strapless double dildo in place in the vagina. This was certainly true in our case so we bought a pair of harness briefs (Packer Gear or Lovehoney) deliberately a size too small and these hold the bulbous end firmly inside my wifes vagina while the longer section fits through the built in O ring and is perfect for pegging me.
We find this far better than a standard dildo in a strap on harness as there is no lost movement due to flex in the harness and my wife loves the sensations she gets as she is pegging me.
I agree with both previous comments. If you're using it to penetrate your partner anally, it is very likely to slip out. Using strapon harness briefs, as already recommend, is a good idea in that case. Generally, my advice would be to start training your kegel muscles (search for kegel balls in sex toys) 😉