Just a thought, but would silence, darkness and rocking work well for you? I've found that very effective for going into trance alongside breath work. Also, one that is a bit less specific and can really be done anywhere could be to run hard on the spot and focus on a single spot. I concentrate and let the chatter of my mind come and go, focus on opening up to spirit. I usually take about 40 minutes (but it will differ for everyone). I either find I surpass the exhaustion and keep going, no longer feeling it, but seeing images and hearing some sound from the spirit I am communicating with, or I give into the exhaustion and go to the ground but still get the same results with images and sound. I found that quite good to do with nature spirits, sometimes I focus on giving my energy to nature whilst doing it and at some points, it has almost felt as if they 'caught me' or gave me soft landing as I came down (not fainting, but head spinning sensation). I've also walked and walked and walked allowing trance to take me that way, I've found dusk was a good time for me doing it that way. And doing specific breathing whilst watching light reflecting on water - this one I found a lovely one for connecting to water spirits, but could be replicated at home with a dish/bowl and a candle.
I heard Alkistis Dimech (of Scarlet Imprint) describe the running on the spot in a recording of The Mirror of Sacrifice talk, and I was really pleased to hear about it as I think it sometimes gets passed over in favour of the drums that people often think of (not that drums don't work, they just aren't for everyone). I'd been using the running since my teenage years, and have found it can be very effective for a certain type of trance. With trance aid tinctures, it really depends on what's in it. I wouldn't use much at all until you feel able to reach trance yourself, but people have differing views on that. I have found Mugwort tea to be helpful. I've found different techniques give different feels to trances and levels of trance for me, and so I'd tailor the herbs to your experience where possible. Though, a friend of mine found Skullcap helpful for SPD and perhaps that may help you relax more easily.