What size between are you trying to thread? with which thread? If you are having trouble try going up a size or two. Ie, if you are trying to thread a size 10, try a size 9 or 8. Other tips for threading needles include

1: cut the thread at an angle to give yourself a point.
2: barely moisten the thread and pinch it together so that all the fibres are laying close to each other (this is what is happening when sewers put the thread to their lips, you don't make it completely soggy with your tongue, just between the lips is sufficient.
3: draw the cut end of the thread through some bees wax, then repeat through your finger & thumb applying lots of pressure. This will also make all the fibres lay closely together.
4: instead of presenting the thread to the needle, do it the other way around, present the needle to the thread. (A friend who does miniature embroidey threads her size 14/12 needles this way)
5 Look for Between needles with a large eye - I know that John James makes these for UK, but I don't know about the USA market.

Hope one of these suggestions helps

I have aced the machine quilting and now doing the hand quilting. Couple of questions 1) how to thread a between needle? That is one tiny hole! My littLe threader does not work 2) better thread weights for betweens What combinations have worked the best, needle size, type, thread weight? Thanks