The best way to thread a needle, no saliva involved! Is to simply cut the end of the thread with a really good pair of scissors and thread immediately, and if it doesn’t go in after the second attempt, just cut the end again. I find it almost always works 1st time.
My tip for jewellery makers is if you are wanting to cut out matching pairs of small shapes ie hearts , stars etc glue 2 sheets of metal together with super glue then cut once. A very small amount of heat vaporises the glue when done.