Hi Ozy,
I sympathize with your frustration and have found that when I follow a set of steps, and eliminate the variables things go much smoother. I would refer you to Elite's website on tuning. I also start with the bowyer's recommended string (material and No. strands), string height, when setting the nocking point. I pick one or two arrows and start with their recommended brace height, on the low side, set a nocking point and shoot fletched arrows into a bale or paper target in front of a bale. I gradually increase the string height, 10 twists will raise the height about 1/4". I then build the rest out, with electrical tape, cut in 1" lengths until I get a favorable results. I am trying to find the spot where the bow is quietest, and gives the best flight.
Once all that is done then I will try paper tuning with bare shafts and fletched arrows. I think, it is easy to want to skip the early steps and jump right to the bare shaft, or bare shaft with BH. Don't it will only get confusing.
Next, have someone stand behind you while you shoot some fletched arrows, that can see what the arrow is doing when it leaves the bow. If you are looking, just focus on the spot and keep both eyes open and see if you can pick it up white or light colored fletching.
If it is possible start with 500 spine, to confirm or reject that arrow. Then the 400, before going to the 340, etc with 160 - 200 gr. points. The lighter points will show up as strong or weak, where a really heavy point might not. Go slow, and make some notes as you go. Good luck.